#44 Don't overwrite modified makefiles

The c_project generator has been modified so that it will not generate
a makefile when one is already present. This allows a user to make
persistent modifications to the content of a makefile.
#11 Removed redundant logic from assembler

The assembler included special cases for DPV instructions under the
assumption that these instructions could not be encoded using the
available instruction space. This assumption is not correct, therefore
special cases are removed.

Also fixed a small bug in the loader. Packages can now be loaded again
using scoped names (::Foo::Bar).