Improve vim HTML template.

Add:
	vim/templates/html.tmp
		-Rewrite (and improve) vim's HTML template file, adding browser
		conditionals and `meta` tags.
Rewrite LoadTemplate() to support dotted filetypes.

Mod:
	vimrc
		-Rewrite `LoadTemplate()` to support multiple (dotted)
		filetypes.
Refine new LoadTemplate().

Mod:
	vimrc
		-Move a part of `LoadTemplate()`'s sub-function
		`LoadFiletypeTemplate()` into another sub-function called
		`SubstituteTemplateFlags()` for modularity.
		-Add function documentation comments.