Initial checks for secret values

[keisau]

Notable changes

1. UnitIsPlayer and other similar functions wrapped with issecretvalue and pcall.

Other changes

1. From Midnight pre-patch, Addons' file modes are converted to 0777 by the game. This will taint the whole repository. To ignore file mode changes, run git config core.fileMode false.
2. Trailing spaces and missing newline in last line in all files are quite a headache. All staged files no longer contain trailing spaces and now has a newline at the end of the file.
3. Added .gitignore.

[frozn]

Thanks for the PR! 👍

About the removed trailing spaces:

1. Unfortunately it's hard to see the "real" fixes in the diff.
2. To be honest, I'd like to keep them.

[keisau]

Thanks for the PR! 👍

About the removed trailing spaces:

1. Unfortunately it's hard to see the "real" fixes in the diff.
2. To be honest, I'd like to keep them.

Modern text editors tend to remove trailing spaces. If this is preferred, please attach a working config like .vscode as a reference. The default config of VSCode, Zed, etc, truncates trailing spaces.