Vulkan ErupteD breaking changes and transition strategy

[Peter Particle]

ErupteD [0] is deprecated (one of its major modules). The project 
content is supposed to be replaced completely. Current state was 
copied into ErupteD-V1 [1] (without deprecation message), neither 
ErupteD nor ErupteD-V1 will be further developed.
The breaking changes and Vulkan 1.1 are implemented in ErupteD-V2 
[2]. At some future point ErupteD will be destroyed and recreated 
with all releases of ErupteD-V2 [3].

Two issues bugged me with the previous design of the binding:
1. versions are not only disconnected from, but also far beyond 
Vulkan
2. too many dub dependencies - if on windows, than platform 
foreign ones

1. this is the reason for the involved transition, ErupteD needs 
to get rid of all releases / version tags to restart with a clean 
slate.
I also extracted the python generator script into its own non-dub 
project, V-Erupt [5]. It was kind of wired to mix two different 
purposes into one project version scheme.

2. the new approach does not require dependencies at all (other 
than phobos / druntime). Platform dependent extensions are 
implemented in form of a parameterizable mixin template. User is 
supposed to mix them into his project and take care of the 
dependencies himself [4]. Platform windows is pre-instantiated, 
as it relies only on druntime. With this approach dub cache stays 
clean from foreign platform dependencies and silences version 
mismatch noise.
While at it, I also removed the DerelictUtil dependency and added 
simple entrypoint loading mechanics. ErupteD-V2 is now fully 
nothrow @nogc and should be -betterC compatible (not tested yet). 
Moreover, no requirement for dub configurations any more.

[0] : https://github.com/ParticlePeter/ErupteD
[1] : https://github.com/ParticlePeter/ErupteD-V1
[2] : https://github.com/ParticlePeter/ErupteD-V2
[3] : 
https://github.com/ParticlePeter/ErupteD-V2#erupted-deprecation-and-upgrade-process
[4] : 
https://github.com/ParticlePeter/ErupteD-V2#platform-extensions
[5] : https://github.com/ParticlePeter/V-Erupt