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.
DisplayBuffer should just focus on providing basic support for folding.
Scanning the structure of the code, looking at scopes, etc is more the
domain of the LanguageMode object.
This corrects a regression where closing an edit session that
is opened somewhere else should not prompt to save since it
won't be lost if closed immediately since it is still open in
another pane.
The status bar view now tracks the active pane item
and hides and shows elements that apply for the active
item such as path, cursor position, grammar, etc.
Just like the cursor clears its goal column when it is moved in any
way other than vertically, the selection clears its goal range (the
range it will attempt to use when adding a selection below) when it
is changed in any way.
Just like the cursor tries to stay in its "goal column" when moving
vertically, here we try to keep the same selection even when adding
across shorter lines.
Previously, logic associated with swapping grammars was a bit
scattered. Now grammar reloading / assignment methods delegate to
LanguageMode directly, and it emits a 'grammar-changed' event when
the grammar changes. Now EditSession and TokenizedBuffer listen for
this event and perform necessary actions for grammar change.
This is more consistent with other range-oriented methods on
EditSession. At this layer, we need to be explicit about what kind
of range we are talking about.
This makes it easy to only assign variables for the information you
need in the iterator. Before, we always forced you to take a match and
a range as the first two arguments even if you weren't using them.
Since buffers are now serialized directly, previous versions of the
EditSession state which used the buffer's path as the `buffer` key
are no longer valid.
