Merge branch 'release-0.2.6' into develop
Fixes #54
Fixes #60
Fixes #56
Update GamePad class
Add class in Input Namespace
Fixes #57
Fixes #63
Fixes #69
Fixes #66
Fixes #62
Fixes #67
Fixes #70
Fixes #72
Fixes #71
Fixes #68
Fixes #73
Fixes a bug in mouse delta computation
Fixes a bug in axis value computation
Update demo

Demo updated to use Input module of Pulsar