* fix excessive graph padding for some fonts
* refactor code to make the position calculations more maintainable
* reduce graph view padding from 2 to 1 character widths in monospace
fonts
* Add generic r2 graph.
* Add Callgraph widgets
* Add more graphviz layouts.
* Fix some edge cases in graphGridLayout that were more likely to appear in callgraphs
* Refactor the code moving some of the logic out of disassemblyGraphWidget making it more reusable