Assembler Simulator Versions Save

• Improved UI layout so the code text area can be expanded vertically
• Highlight code when clicking an instruction or label address
• Stack area is highlighted
• Labels need to match case in code

Thx a lot @mrclay for the pull requests!

• MOV, ADD, SUB, INC, DEC and CMP commands now can use the SP register. This allows the usage of other registers as frame pointer (using MOV from SP), allocating and clearing of stack for local variables and function arguments using SUB SP,... / ADD SP,....
• Support for indirect addressing with offsets for all general purpose registers. All of them can be used as frame pointer to access local variables on the stack. Syntax: [D-3].
• Memory locations referenced by general purpose registers can be highlighted.
• List of labels and their values is visible in a separate panel.

Many thx to @SergeyVlSorokin for this awesome pull request!

• Added HLT instruction to stop the execution.
• It is possible to address memory with [SP+NUMBER]. See instruction manual for more details.
• Single operand instructions like INC throw an error when two operands are specified.

Bugfix: DIV operand didn't support all parameters as written in the documentation