McCortex 0.1.1

Changelog:

• server command: read graph from disk
• vcfcov command: default to low memory mode
• build,clean commands: write sorted graph files
• clean command: faster cleaning
• fix rare multithreading bug in db_unitig.c
• mccortex-server.py: multithreaded HTTP JSON server
• hash_table.c: faster initialisation of large hash tables
• update dependency libraries
• better integration tests