GUI Code

Reduce some code and add ok and cancel button on x value and style menu
GUI and Ploting Code

1. add function to plot
2. add option to set line width
3. solve some problem
4. add option to calculate equation
5. add option to reset ploter screen
6. prepare to add set x axis and y axis limit
Merge branch 'master' of https://github.com/kanathips/math_ploter

Conflicts:
	GUI.py