ADDED: util/Parallel.java

 * Original source:
   https://github.com/pablormier/parallel-loops/blob/master/src/main/java/es/usc/citius/common/parallel/Parallel.java
CHANGED: add features into Parallel.java
WIP: parallel code asset hash checking

 * parallel code for assets/objects/* hash checking
 * parallel code for assets/virtual/foo hash checking
FIXED: hashing
 * hash derp
 * build fix
 * hash check performance fix
Merge pull request #755 from jikuja/feature_parallel

RFC: parallel thingies