Increase Wither Spawn

This mod, made for 1.7.10 yet double the spawn rate of Wither Skeleton in fortress. It has no config or customizations yet but will be surely implemented in a 2.0

It also seems to be useful when you're using the mods "IncreaseMobs" due to a bug of it, removing completely the spawn of wither skeleton (?). If you use this mod with "IncreaseMobs", it will re-allow the wither skeleton to spawn. 

The v1.1 is compatible with Magic Cookies's fortress! It drastically increase their number

Enable the mod and voila!

Feel free to include this mod in any modpack published on curseforge! Also feel free to suggest new things.