This commit moves all the logic that deals with the language server
(from HackStudio) into a LanguageClient class, provides some functions
to make constructing them easier, and makes all language servers use a
singular IPC definition.
Also fixes the FIXME about making the autocompletion async.
This makes adding language servers in the future significantly less
duplicate-y, and significantly easier :^)
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 also resolves some typing issues that only 'accidentally' worked, like declaring
a function to return type A, and the definition actually returning type B (which works
if type B is a subtype of type A). I like to call these "ninja imports".
To prevent problems like this in the future, I put all globals in a HackStudio.h.
I'm not sure about the name, but main.h and common.h felt wrong.
