Contexts

[dabbler0]

Add support for parsing contexts. A parsing context is a prefix, suffix, and indentation level that are added to a block before it reparses, then removed afterward. For instance, the coffeescript when block:

when a
  do b

Has the parsing context with prefix switch\n, no suffix, and an indent of . So before being passed to the parser for reparsing, it becomes:

switch
  when a
    do b

Then after parsing, the parser wrapper layer looks for the block at the correct location in the result, clips it out, and returns that, to give a block that reads with the original text..

[davidbau]

s/backtick/underscore/

[davidbau]

It's odd that this merge would leave us in a state when switch cases can be dragged around, but then they can be dragged out to regular statement context where they're illegal.

What would it take to:

(1) Configure an enumeration of parsing contexts on the side and
(2) Tackle droppability rules at the same time?