parse RF lines correctly in hmmscan output
do not 'clean' splint and scan-build targets

remove obj folder only if cleanup is called. this prevents splint and
scan-build to rerun every time make clean was used.
remove amalgamation.c on clean

closes #343
Merge pull request #344 from Garonenur/make

do not 'clean' splint and scan-build targets
allow visitors without feature node handlers

Closes #346.
Merge pull request #341 from satta/hmmscan_parse_fix

parse RF lines correctly in hmmscan output
Merge pull request #347 from satta/feature_visitor

allow visitors without feature node handlers