Support installing Python modules from general URL sources on MS Windows

[wenzeslaus]

G7:g.extension supports compiling any accessible code on Linux and other operating systems with make and other needed tools installed (doc). While compiler and developer libraries are required for C and that would be probably hard to provide on MS Windows (please, correct me if I'm wrong), Python modules do not really need any extra tools and running Python and copying to the right directories is probably all what the Makefile does.

I suggest to implement basic compilation replacement in g.extension for Python modules so that the following is possible also on MS Windows:

g.extension r.example url=github.com/johnsmith/r.example
g.extension r.example url=trac.osgeo.org/.../r.example
g.extension r.example url=http://example.com/.../r.example?format=zip
g.extension r.example url=/local/directory/r.example/

This should be ideally 7.2.2 milestone which does not exist. It is an enhancement, but it is partially a missing/expected feature/behavior and the implementation hopefully should not destabilize g.extension.

[wenzeslaus]

This is a feature, so next minor release.

[neteler]

Ticket retargeted after milestone closed

[martinl]

All enhancement tickets should be assigned to 7.6 milestone.

[martinl]

Ticket retargeted after milestone closed

[martinl]

Ticket retargeted after milestone closed

[martinl]

Remove Milestone from Addons bugreports.