Minor changes in the doxygen documentation
Added sequence diagram
First working implementation of linear equations
Moved LinearEq methods to source file. Removed InvalidLinearEqException.
Added new test cases to ParserTest
Updated doxygen documentation of several classes
Added comment in SyntaxTree
Updated doxygen documentation of QSimpleCalc class
Fixed focus policy of help button
Adde missing license hader in several files. Updated help string. Showing error with red color