Adds importing of animated image formats using QImageReader
Merge pull request #224 from czxcjx/czxcjx

Adds importing of animated image formats using QImageReader
Fixes #223
Fixes #223
Merge pull request #225 from czxcjx/czxcjx

Remember last size used for polyline tool
Merge branch 'master' of https://github.com/pencil2d/pencil
Merge branch 'master' of https://github.com/chchwy/pencil2d
Merge branch 'master' into refactor/layer-manager