Organize OpenEmulator into subprojects

[tobier]

Marc S. Ressl has done a lot of work developing OpenEmulator over the years. Now, with him no longer working on the project, it's time for new developers to pick up where he left off.

OpenEmulator has many individual components that can be developed, compiled (and tested?) individually. The main source tree should be divided into subprojects, under the OpenEmulatorProject organization. I propose the following subprojects:

• OpenEmulator - core repository with base build scripts, documentation, resources and GUI source code.
• libemulation - emulation library
• libemulation-hal - libemulation hardware abstraction layer
• libdiskimage - disk image library
• libutil - common utility library

[tobier]

Unfortunately, there is no good way of handling dependencies without having duplicate modules in Git. For now, clean up the source tree and leave in one repository.