Update .gitattributes to prefer LF (#12816)

Part of #12387

Summary of the issue:
The NVDA code base uses a mix of CRLF and LF style line endings, with the preference being CRLF.
LF style endings have been introduced prior to lint checking, and can causes issues when moving code or making changes.
Many IDEs will normalize the line endings when editing files, causing larger than intended diffs of files with mixed line endings.
Instead, we should normalize all line endings of text files to LF and ensure that all files are committed with LF line endings.

Specific files should be excluded from normalization such as:

files used by translators, as we are uncertain of the side-effects here
binary files
git allows independent configurations between line endings used when a developer checkouts out code locally, and when code is committed to a repository.
IDEs are often better suited for different line endings, with LF line endings becoming more and more standardised.
However, NVDA is Windows based development, where CRLF line ending usage is commonly default or compulsory.
Developers can checkout code locally, using whatever line endings they prefer or their IDE requires, using git config.core autocrlf.

We can configure what line endings we commit to the repository with .gitattributes.
This is set on a repository level.
As what line endings we commit with is agnostic to what is checked out, the decision is based on what works best for the repository.
Unix style line endings usage and support continues to increase on Windows and LF files.
LF tends to be better supported by Unix style developer tools such as git.
LF uses less data than CRLF.

Author: seanbudd

.git-blame-ignore-revs

@@ -1,3 +1,6 @@
+# Documentation: https://git-scm.com/docs/git-blame#Documentation/git-blame.txt---ignore-revs-fileltfilegt
+# Usage: git config --local blame.ignoreRevsFile .git-blame-ignore-revs
+
 # Normalize line endings in t2t files
 e6a639bfe237ff7f98c4cbec2094a34ac4b879db
 # Migrate t2t to markdown

.gitattributes

@@ -3,3 +3,84 @@
 # Every person expected to commit po files should change their personal config file as described here:
 # https://mail.gnome.org/archives/kupfer-list/2010-June/msg00002.html
 *.po filter=cleanpo
+
+eol=lf
+*	text=auto
+
+# Files which should not be renormalized
+*.dic   -text
+*.po    -text
+
+# Git files
+.gitignore       text
+.gitattributes   text
+CODEOWNERS       text
+
+# Documentation files
+*.md     text
+*.txt    text
+
+# Scripts
+*.ps1    text
+*.bat    text
+*.nsi    text
+
+# Config files
+*.ini    text
+*.yml    text
+*.robot  text
+*.subst  text
+Doxyfile     text
+Makefile     text
+
+# Other files
+*.def text
+*.css text
+*.svg text
+
+# Source files
+# ============
+# Python Sources
+*.py     text diff=python
+*.pyw    text diff=python
+*_sconscript  text diff=python
+sconscript    text diff=python
+sconstruct    text diff=python
+# C++ Sources
+*.c     text diff=c
+*.cpp   text diff=cpp
+*.h     text diff=c
+*.idl   text diff=c
+*.acf   text diff=c
+
+# Binary files
+# ============
+# Python binary files
+# *.db     binary
+# *.p      binary
+# *.pkl    binary
+# *.pickle binary
+# *.pyc    binary
+# *.pyd    binary
+# *.pyo    binary
+# # Compiled C++ Object files
+# *.slo   binary
+# *.lo    binary
+# *.o     binary
+# *.obj   binary
+# # Precompiled C++ Headers
+# *.gch   binary
+# *.pch   binary
+# # Compiled C++ Dynamic libraries
+# *.so    binary
+# *.dylib binary
+# *.dll   binary
+# # Compiled C++ Static libraries
+# *.lai   binary
+# *.la    binary
+# *.a     binary
+# *.lib   binary
+# # C++ Executables
+# *.exe   binary
+# *.out   binary
+# *.app   binary

projectDocs/dev/codingStandards.md

@@ -3,17 +3,20 @@
 Python code style is enforced with the flake8 linter, see [`tests/lint/readme.md`](https://github.com/nvaccess/nvda/tree/master/tests/lint/readme.md) for more information.
 
 ### Encoding
+
 * Where Python files contain non-ASCII characters, they should be encoded in UTF-8.
-    * There should be no Unicode BOM at the start of the file, as this unfortunately breaks one of the translation tools we use (`xgettext`).
-    Instead, include this as the first line of the file, only if the file contains non-ASCII characters:
-        ```py
-        # -*- coding: UTF-8 -*-
-        ```
-    * This coding comment must also be included if strings in the code (even strings that aren't translatable) contain escape sequences that produce non-ASCII characters; e.g. `"\xff"`.
+  * There should be no Unicode BOM at the start of the file, as this unfortunately breaks one of the translation tools we use (`xgettext`).
+  Instead, include this as the first line of the file, only if the file contains non-ASCII characters:
+
+  ```py
+  # -*- coding: UTF-8 -*-
+  ```
+
+  * This coding comment must also be included if strings in the code (even strings that aren't translatable) contain escape sequences that produce non-ASCII characters; e.g. `"\xff"`.
     This is particularly relevant for braille display drivers.
     This is due to a `gettext` bug; see [comment on #2592](https://github.com/nvaccess/nvda/issues/2592#issuecomment-155299911).
-* New files should contain `LF` line endings, however NVDA currently uses a mix of LF and CRLF line endings.
-See issue [#12387](https://github.com/nvaccess/nvda/issues/12387).
+* Text files should be committed with `LF` line endings.
+Files can be checked out locally using CRLF if needed for Windows development using [git](https://git-scm.com/book/en/v2/Customizing-Git-Git-Configuration#_core_autocrlf).
 
 ### Indentation
 * Indentation must be done with tabs (one per level), not spaces.