WIP: Bring docbrowser into this decade

[NattyNarwhal]

Docbrowser has been broken due to the removal of all of its HTML renderers; and carries functions I'm pretty sure don't actually work anymore. This is a branch to start zorching legacy crap and try to refactor tools and upgrade them to the latest toolkit. Right now, I only care about docbrowser, but it seems other tools will likely need help.

What I've done for docbrowser as of creating the PR:

• ripped out everything but WebKit, which will be refactored to use WebKit2

• added a null renderer to get the thing running in spite of problems

• removed all contributions related functionality

• split out classes from a single god file in browser.cs to several

DO NOT MERGE YET: My next plan is to upgrade docbrowser into a GTK# 3 application. THis might require build system bypass/surgery.

[NattyNarwhal]

So far:

• We have working GTK# 3 and WebKit 2 based docbrowser

• But it doesn't work too great; WebKit 2 doesn't let you cancel requests from the event, so we have to use Stop; which leaves us to race conds that trigger; and I nopped out the drawing for a control instead of porting it to Cairo

• I semi-bypassed the build system for docbrowser; it builds but it'll pass flags for GTK and WebKit itself

• It'd be nice if GTK# 3 had HeaderBar support, so we can use CSDs

• Mono.Options should be a NuGet dep

[ZenTauro]

@NattyNarwhal any updates on this?