Refactor objs, mobobjs into array (#225)

Reuse array elements for fast item access
Items can no longer be referred to from pointers,
only using integer IDs which are also array indices.
This also means changing tile things to arrays.

Add CArrayReserve
Optimise CArrayDelete using memmove

Fix memory leak with AStar path

Fix high scores not displayed when playing last level

Fix some other memory leaks
Merge remote-tracking branch 'origin/master'