Generation implementations

[Therzok]

https://github.com/mono/gir-sharp/tree/master/src/Gir/Generation

• [x] ~Alias~
• [ ] Array
• [x] Bitfield
• [ ] Callback
• [ ] Class - Stubbed out
• [ ] Constant
• [ ] Constructor - Stubbed out
• [x] ~Direction~
• [x] Documentation - Done via IndentWriter.WriteDocumentation, needs a bit of rework (IPreGeneratable and do it automatically in IGeneratable extensions
• [x] Enumeration
• [ ] Field - WIP @Therzok
• [ ] Function
• [ ] Implements
• [x] ~Include~
• [ ] InstanceParameter
• [ ] Interface - Stubbed out
• [x] Member - Done, but needs a bit more rework to hex formatting smarter and not hacky
• [ ] Method
• [x] ~Namespace~
• [x] ~Package~
• [ ] Parameter
• [ ] Prerequisite
• [ ] Property
• [ ] Record -WIP @Therzok
• [x] Repository
• [ ] ReturnValue
• [x] ~Scope~
• [ ] Signal
• [x] ~TransferOwnership~
• [x] ~Type~
• [ ] Union
• [x] ~Varargs~
• [ ] VirtualMethod