Add ol.structs.LRUCache
Port ol.TileCache to ol.structs.LRUCache
Port WebGL texture cache to ol.structs.LRUCache
Remove ol.structs.LinkedMap
Use an object literal rather than a class for LRUCache entries
Rename object properties so compiler can rename them
Merge pull request #176 from twpayne/lru-cache

LRU Cache
Remove unnecessary undercores, thanks @fredj
Merge branch 'master' of github.com:openlayers/ol3 into wmscaps