First step of restructuring for #665 and #681
Created branch for tickets #665 #681
Implemented ticket #682 "Add 'combobox' to window layouts"
Implemented ticket #689 "Secondary axes improvement"
Replaced the error code for the matrix dimension mismatch of the hcat and vcat function with the proper generic error message, Related to ticket #646
Implemented ticket #668 "'declare' should be includable"
Implemented ticket #690 "Disable automatic UI element focusing"
Fixed issue #688 "Bug within plot options"
Fixed issue #686 "Issues with 'getkeyval()'"
Fixed issue #685 "Bug in matrix mode"