Merge pull request #65 from kamalpreetgrewal/master

switching to qgraphicsitem and qgraphicslineitem classes and correction of line's bounding rect
updates readme
Undo/Redo operation in Text
Saving text id and text width
Merge pull request #68 from CharuChopra84/master

Undo/Redo operation in Text
Merge pull request #67 from ChanKaur/chan

updates readme
rectifies crashing occurring when undostack reaches its top