Added delete of outputs/inputs/changeprop/lesions to the undo system so that deleting objects in the network can trigger them. Bugfix for changed props being overwritten. Several GUI behaviours corrected to right inconsistencies
Changed normal projects to save components using XML safe filenames. Previously used spaces in filenames
Cleaned up the undo system, made the width and handles of projections scale on retina displays. Enables Hidpi icons for retina displays, although some icons need updating to hidpi versions