If file is downloaded from certain Git interfaces such as GitHub,
the CRLF lineendings are not presevered. So it's best to disable line
normalization for all iCalendar files and all systems.
The following settings will always checkout iCalendar files with CRLF
line endings no matter the user's system configuration of
core.autocrlf setting and core.eol setting.
This patch adds a new .gitattributes file to distinguish the end of
lines of the iCalendar files located in the repository and for Git to
not normalize and convert end of lines. The iCalendar format requires to
have CRLF line endings. All other files in the repository can have
native EOL. On *nix alike systems LF and on Windows CRLF which Git can
convert properly on checkouts.
