- added rename icon in layers list
- mutualized CSS for edit icon between palette manager and layers list
- new CSS file icons.css for actions/links/buttons using icons
- layers are no longer retrieved by name, but by index
- mutualized shape tools common code in a ShapeTool class
- when holding shift and drawing a frame, the ratio is preserved
- selection and shape tools now support the mouse to leave the drawing
area
- shape tools can go 'outside' the drawing canvas
- Frame set/getPixel now check the pixel is in range instead of crashing