Bugfix - when searching for the smallest key larger than the given key (or equal
to it), didn't handle the case in which there are no more small keys that are 
larger than the given key in the left side of the node. In such case, we should
return the current node. Now doing it.
Grammar error.
Added successful prints for the insert and remove operations.
Forgot to return the key from the function. GCC without -Wall didn't catch that, and it's amazing that stuff actually work...
Added more strict build options.