Fixed various cursor issues and connector issues.

Implemented Cursor management in StateMachine
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Fixed following issues:
1) Pan Mode Cursor issue with window selection (MAGN-464)
2) Cursor problem in Library view (MAGN-537)
3) Info bubble overwrite cursor (MAGN-548)
4) Connector cursor changes for compatible connection

Fixed Node connector issues
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1) Crash while connecting output to output for nodes without input port (MAGN-637)
2) Modify snapping behavior to only snap for compatible connection