Recognize suffixed compiler names in Makefile.

E.g. `CXX=g++-4.7 make` now works,too.
Simple ART Dictionary implementation
Added file splitting tool

Added tool to generate two data sets from one turtle file for bulk
insert/insert/delete tests.
Specify libraries and dependencies in Makefiles

Libraries are included with -isystem, dependencies with -I
Moved header files, fixed test.
New perftest executable

Loads turtle data into all dictionaries in succession.
Fixed generate-files tool
Measure memory usage in perftest
Enhanced dictionary API + unit tests
Work on perftest
Removed DictionaryLoader, fixed parser (+ tests)
Added B-Tree dictionary
Fixed parser, perftest
Fixed implementation error
Clean up ReverseIndexART implementation
Modified ART to avoid memcpys.
Clean up performance test code.
Updated README.
Added B+-Tree dictionary.
Fixed perftest