Disassembly View (Source Code): add setting for tab-width

[Simon Sobisch]

Is your feature request related to a problem? Please describe.
Tab-indented sources are often hard to handle because the source view uses a width of 8.

Describe the solution you'd like
Add an option to set the tab-width, possibly a default in the settings and a manual override?

Describe alternatives you've considered
buy a bigger monitor ;-)