Unit ID's are not recycled

Currently the ID number of a unit is raised incrementally forcing the system to 
keep track of every single placed unit forever. This includes each individual 
piece of a tether which can quickly become a large amount of data. As old units 
are destroyed they are still stored in memory as a destroyed unit which is very 
inefficient and the greatest cause of crashes in long term games. System needs 
to be rewritten so that craters become permanent part of the map itself while 
all destroyed units become 'voids'. A function needs to be written to check for 
voided units so that those unit numbers can be overwritten being much more 
efficient of memory.

Original issue reported on code.google.com by Donkyhotae on 30 Sep 2012 at 7:05

wgrand08 / tether

Unit ID's are not recycled #278