Objects and binaries are now put in neat bin/ and obj/ directories matching the build configuration. This also means that a release and debug build are allowed to coexist, since they won't overwrite files related to each other.
This also thins out the gitignore, and removes build/ from it since it is now a valid directory (where we put the Make buildsystem files).
This commit makes a new build/ folder which contains auxiliary
Makefiles that are used to assist the build.
In theory, later on, (hinted by the documentation of build/core.mk),
it may be possible to even add IOP target support, but for now, I have
not yet added this to the buildsystem. It should be relatively easy, however.
ProDG documentation implies `relapp.cmd` is intended to be used if
the executable in question uses SN's REL system for dynamically linked
libraries. I don't think this is used, so switch to the standard SCE `app.cmd`.
I also added some untested attempt at also allowing windows hosted builds.
For some reason I couldn't get it to play nice with a "loose" prodg install,
I could only get everything to work after I installed prodg proper
