Comments to indicate status of functions

Each new funciton to trees.c has a comment to indicate the current
status of the functions (ie working, not working, unfinished).
Updated professors library files

The library files have been replaced by the versions from Lab4.zip. The
professor's releaseBST has been commented out, as the assignment asks
for a function by the same name.
Fixed some functions

isBalancedBST needed to be fixed for two special cases. BST2Array and
allocBalancedBST have been worked on.
rebalanceBST finished

still needs testing
Updated status tags on functions
Merge remote-tracking branch 'upstream/master'