Add sgml-mode and some derived modes
Remove dependency on dash-functional
Document how to dim other keywords
Merge branch 'sgml-modes' of github.com:paradoxxxzero/color-identifiers-mode

Conflicts:
	color-identifiers-mode.el
Handle old python.el gracefully
Update instructions for enabling permanently

Thanks to @yasuyk for the fix (ankurdave/color-identifiers-mode#9).
Remove calls to defvar-local, which needs Emacs >= 24.3
Add exclusion regexes. Implement highlighting for Objective-C.