Merge with develop.
1. Bug fixed: tool shortcuts doesn't work
2. Simplified the tool change related code.
ToolSet: simplified structure, remove drawPalette.

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branch : develop
ToolSet: remove magnifyButton

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branch : develop
ToolSet: rename varibales.

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branch : develop
ToolSet: remove unused signals, rename m_pEditor => m_editor

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branch : develop
ToolSet: simplified newToolButton()

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branch : develop
MainWindow2: sould not show Preference at beginning.

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branch : develop
ToolSetWidget: rename class ToolSet => ToolSetWidget

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branch : develop
Merge with develop, ToolSetWidget cleanup
Merge branch 'hg'