Update searchtree library

Implemented depth-first search of the neume search tree, which searches
for a payload in the tree and returns the neume typeid, name, and edge
    weights along the path from the root node to the target node.
Search tree melodic movement

for staffless neumes, the melodic movement of the neume can not be
    derived from the pitch. Therefore, a DFS of the neume name is
    performed on the search tree and the edge weights of the path from
    the root node to the target node are used as the relative integer
    pitch differences.