Make TokenizedBuffer select its own grammar, not LanguageMode
Make TokenizedBuffer select its own grammar, not LanguageMode

This is part of an effort to disentangle LanguageMode, DisplayBuffer,
and TokenizedBuffer. It should be easy to create a DisplayBuffer
without creating an EditSession… let's get the dependencies flowing
in a single direction.

TShapinsky/status-bar,ali/status-bar,devoncarew/status-bar,pombredanne/status-bar,mertkahyaoglu/status-bar,Abdillah/status-bar