Revamp all the Makefiles (thanks @fincs @WinterMute) ...

... dependencies are now properly handled (e.g. header changes, etc.)

Add build system for fusee

Use specs file, remove -nostartfiles

Fix Makefile

Adapt code to match last commit, link in bpmpfw_bin(_size)

Rewrite the memory map-related code... ...

...other style fixes, etc.

Move source files to src/, add Makefile, fix all build and linkage errors, etc.