Modified how callbacks work, introduced a parameter struct and an
internal iterator state struct
Modified callbacks to work using new callback system
Started working on revamping tests for iterate
Added functions for initializing and freeing it, and a function for
freeing parameter structs as well as some bugfixes
Changed name of the substring stack struct
Added some more printing data to print_bit_vector()
Created a function for freeing the internals of a tree without freeing
the tree itself
Changed s_to_BWT() to snake case
Added a results-struct for mums as well as an initialization function
for parameter structs
Added a results struct as well as an initialization function for
parameter structs
Modified to use the new callback function
Made s_to_BWT() snake case
Rewrote tests to match the new iterate function
Updated documentation
Merge branch 'develop' into parameter_struct

Conflicts:
	src/applications/mum.h
	src/core/iterate.c
	tests/core/check_iterate.c
Removed unnecessary forward declarations
Updated MEMs to use new iterate-format, and updated documentation
Modified tests to check for leaks
Fixed a leak in s_to_bwt()
Modified tests to check for leaks