Merge pull request #16 from smashwilson/cleanup-makefile

Makefile cleanup.
Rename hashtable tests.
stringtable instead of hashtable.
Rename the existing hashtable to stringtable.
Template ptrtable test suite.
ptrtable signatures.
First ptrtable test.
Use separate includes for different hashtables.
seg_ptrtable implementation.
ptrtable is up and running.
Adapt the rest of the tests while I'm at it.
Stale references to seg_symboltablep.
Pluggable table implementation.
putifabsent test.
Rename it to a plugtable for brevity.
The rest of the tests for plugtable.
Merge pull request #18 from smashwilson/hash-proliferation

Additional hashtable implementations
Merge branch 'master' into object-model

Conflicts:
	Makefile
	tests/unit/suite.c
Include the new tests in the build.