Editors now communicate with the c++ language server when openning and
editing c++ source files, and go through the language server to get
autocomplete suggestions.
This commit adds a new GUI widget type, called CodeDocument, which
is a TextDocument that can additionaly store data related to the
debugger.
This fixes various bugs and crashes that occured when we switched
between files in debug mode, because we previously held stale breakpoint
data for the previous file in the Editor object.
We now keep this data at the "document" level rather than the Editor
level, which fixes things.
