template_deleted event should run before the side-effects.

Just like the other template events.
A method to clean up the files the compiler generates.
updating_stylesheets fires before stylesheets are updated.

This wasn't ever fired previously. In keeping with it's name, the
event is moved to just before stylesheets are updated.
updated_stylesheets is an event that runs after stylesheets are mass updated.
compilation_starting is an event that fires before a single stylesheet is compiled.
Allow skipping the initial update when watching files.
Allow the caller of watch specify additional watch
directories and to receive raw filesystem change events.
Documentation improvements based on code review.

Code review comments were for commit cc3c13ab93f41b81743f3845083c3a3d688efa3d.
Grammar is hard.
CHANGELOG updates for sass compiler improvements.
Don't expose this capability as a documented feature.
Sourcemaps are not always provided.
Merge branch 'support_compass_watching' into stable
Merge remote-tracking branch 'nex3/stable' into stable

Conflicts:
	doc-src/SASS_CHANGELOG.md
Merge branch 'stable'

Conflicts:
	doc-src/SASS_CHANGELOG.md
	lib/sass/plugin/compiler.rb