Ignore errors from libs in node_modules folders

[BendingBender]

I've tried a few different things here but it seems that ignoring diagnostics from node_modules folders is a good enough workaround.

An actual solution for this would be support from tsc to allow type-checking project-local .d.ts files while skipping .d.ts files from node_modules. The way things are right now, skipLibCheck will disable type-checking .d.ts files everywhere which we definitely don't want. On the other hand, skipping type-checking for types from node_modules would bring enormous performance improvements, most time is spent by checking types there.

I've also tried to mess a bit with tsc, mostly by monkey-patching stuff. The problem is that it's pretty much impossible to know in advance which .d.ts files are required to correctly type check an application and which ones not. It mostly boils down to .d.ts files exposing stuff in the global scope or declaring modules with different names than the module they belong to. Most other cases should be discoverable by analyzing for imports, <reference ... directives and the like.

Fixes #45
Fixes #76
Fixes #30