Major code cleanup and addition of config files for easier configuration management.

Draft release with major code cleanup and addition of config files for easier configuration management.

Performance has not been benchmarked against v0.1.7 yet.

Added merge command.

Merge merges two existing BIGSIs by samples.
Duplicate samples with be renamed but both will be kept.
BIGSIs must have been built with the same parameters.

Build command accepts a max_memory command. If the index will exceed this max memory the graph will be built with a build and merge strategy, first building the largest index that will fit in the available memory, building a second index and merging until the index is complete.

v0.1.5 release