* Set svn:keyword Id property on a few files.

Note to developers: use that chunk in your ~/.subversion/config:

[miscellany]
enable-auto-props = yes

[auto-props]
*.m = svn:keywords=Id
*.h = svn:keywords=Id
*.mm = svn:keywords=Id
*.c = svn:keywords=Id
*.cpp = svn:keywords=Id
*.pch = svn:keywords=Id
*.command = svn:keywords=Id
*.pl = svn:keywords=Id
*.pm = svn:keywords=Id
*.py = svn:keywords=Id
*.sh = svn:keywords=Id
*.txt = svn:keywords=Id
*.html = svn:keywords=Id
*.php = svn:keywords=Id