Mono project export

[neikeq]

Just a WIP, but worth being merged at this point.

TODO (not in this PR):

• Make it use the export templates compiled with mono, somehow.
• Fix _export_begin not being called with the "Export PCK" option. I used this patch for testing purposes but, as you can see, it doesn't take Debug/Release and the output path into account:

  @@ -596,6 +596,7 @@ EditorExportPlatform::ExportNotifier::~ExportNotifier() {
   }
   
   Error EditorExportPlatform::export_project_files(const Ref<EditorExportPreset> &p_preset, EditorExportSaveFunction p_func, void *p_udata, EditorExportSaveSharedObject p_so_func) {
  +	ExportNotifier notifier(*this, p_preset, false, "", 0);
   	//figure out paths of files that will be exported
   	Set<String> paths;
   	Vector<String> path_remaps;

[neikeq]

cc @karroffel @endragor Follow up from #11580 (review). I don't know if this will break anything.

[exts]

@neikeq so just to test I grabbed master and built all the export templates for windows 10 64 bit.

In the https://bitbucket.org/G4MR/godot-breaker/src bin folder you should find the release/debug executables that I ran which gives me errors.

• One error I get is mono core api hash mismatch which doesn't seem right because I copied/pasted the generated dll's that were built with my version of mono (latest using vc++ 2017 build tools)

• Another error I get is SOMETIMES when I start the game it'll tell me a non existent signal exists from StartGame to BlockDestroyed and other times I could load it up and nothing pops up. When this happens with the below image the restart button stops working completely (once the game ends) which is strange. In the editor I don't get such error or issue so the signal's are working and used correctly.

• Third issue I forgot to mention is that the release build doesn't play sounds when the brick breaks which is also strange, although sometimes the debug version works how it should.

https://i.imgur.com/wta4Cb4.png

You can see all the source in that repo if you want to attempt to reproduce. Hope this helps with the ongoing efforts for getting exporting stable. 👍

[akien-mga]

One error I get is mono core api hash mismatch which doesn't seem right because I copied/pasted the generated dll's that were built with my version of mono (latest using vc++ 2017 build tools)

I think the core API changes between tools=yes and tools=no builds, so you need to regenerate the mono glue for each build.

[exts]

hmm, I'll test it again later

[hpvb]

Cherry picked into 3.0.3