Idea: default to display register values as Decimal instead of Hexadecimal

[Nilaos]

Many novice assembly programmers are either still learning or have not learned to fluently read hexadecimal values.

While this is the more native way to read and understand assembly-level instructions and data, to make working in assembly more approachable it may be preferable to have the default register view set to Decimal instead of Hexadecimal in config.rs.

[Nilaos]

This may be linked to #178. Also related (loosely) is #105, which requested the feature originally.