Migrated the latest 1.5 world changes to fix mystcraft. Fixes #776, #1036

This build brings forth an important change to how world data is stored :

* New worlds will no longer be created in server root. All new worlds will
now be placed in the overworld root which is identical to Forge/FTB.

To help assist migrations, I have modified the old Forge->CB migration
code to now migrate from CB->Forge. What this means is, all world data
stored in world_name folders in server root will be migrated over to your
main world's folder. Example : in pre-legacy builds 32+, mystcraft data would
be stored in world_myst/DIM_MYSTXX, this folder will now be moved to
mainworld/DIM_MYSTXX where mainworld is whatever you named overworld.
However, if you are migrating from legacy 31 and under then mystcraft data
is stored in world_myst/ageXX/DIM_MYSTXX. To migrate properly, you must
move all data from ageXX into DIM_MYSTXX, move DIM_MYSTXX back to
world_myst root then load up this build to finish the migration to
overworld/DIM_MYSTXX. If you have any questions please contact us on
irc.esper.net #mcportcentral.