Divide option

removed a line of stuff from MathOperationLinear
**TODO***
comment that line properly
Added operations to the operation drawer
+ Created a class MathSourceView which will be the source for dragging MathObjects
* Modified the add, subtract and multiply operations to have a small padding around their operator

Signed-off-by: Mark Kamsma <mark@markkamsma.nl>
Wat zooi in de startup, kun je er uit halen als je wilt.

En de divide compleet!
Added dragging to the drawer

Signed-off-by: Mark Kamsma <mark@markkamsma.nl>
Merged in Ivor's divider operator

Signed-off-by: Mark Kamsma <mark@markkamsma.nl>