README updates.
README updates.

Fixes #32. Fixes #33.

drewet/entityx,alecthomas/entityx,arvidsson/entityx,alecthomas/entityx,drewet/entityx,Bablawn3d5/entityx,arvidsson/entityx,alecthomas/entityx,jarrettchisholm/entityx,Bablawn3d5/entityx,Bablawn3d5/entityx,jarrettchisholm/entityx,arvidsson/entityx,jaynus/entityx,jaynus/entityx,drewet/entityx,jarrettchisholm/entityx,jaynus/entityx