Support for .NET core

[photex]

Ahoy!

I do not expect this to be merged as is. But to get the conversation going I wanted to open a PR with the initial attempt.

I can download netcoredbg, and I can launch using it. Breakpoints don't get resolved yet, among other issues I'm sure.

I had to base this on the 0.10.1 tag because I couldn't use the package as is on 'master'. I'm happy to rebase there though.

[photex]

Ok, @daveleroy I rebased, but now I see the following error:

Traceback (most recent call last):
  File "/home/chipc/.config/sublime-text/Packages/Debugger/modules/debugger.py", line 69, in get
    instance = Debugger(window, skip_project_check=skip_project_check)
  File "/home/chipc/.config/sublime-text/Packages/Debugger/modules/debugger.py", line 106, in __init__
    self.project = Project(window, skip_project_check)
  File "/home/chipc/.config/sublime-text/Packages/Debugger/modules/project.py", line 17, in __init__
    if not skip_project_check and not Settings.global_debugger_configurations:
  File "/home/chipc/.config/sublime-text/Packages/Debugger/modules/settings.py", line 17, in __get__
    return SettingsRegistery.settings.get(self.key, self.default)
AttributeError: type object 'SettingsRegistery' has no attribute 'settings'