fastmap 1.1.0.9001

Closed #25: Added the following functional methods to fastmap (#29):
- map(), map_with_key()
- filter(), filter_with_key(), filter_key()
- modify(), modify_with_key()
- walk(), walk_with_key()
Changed fastmap's $has() method to use C++ contains() method (which is new in hopscotch-map 2.3.0).
Closed #24: Added a $clone() method to fastmap. (#26)
Fixed #27: If a fastmap object has no holes in the lists storing keys and values, and then it is serialized and then unserialized, the new fastmap would contain zero items. (#28)
Faster implementations of fastmap $keys() and $as_list() methods.
Updated hopscotch-map library to 2.3.0.

fastmap 1.1.0

Fixed #13: fastmap.cpp now explicitly includes the algorithm header, which is needed on some platforms to successfully compile.