Fixed '/warp assets' when limits are disabled, removed name null checks
The removed null-checks when converting the invited-player-ids to names
does not mean that this problem has been solved. Rather the problem
affects the whole plugin and needs to be solved globally. It has been
registered as #15.
Fixed SQLite Migrator using MySQL dialect.
Rewrote Markers to use one method for all updates, fixed dynmap for now
The rewritten interface puts control over the conditions to display a
markers for a warp completely in the implementation.
Remaining bugs in the dynmap implementation have been fixed, as far as
they are caused by MyWarp. There seems to be an issue with moving a
marker to a different world but that should not be caused by MyWarp.