Changed index literals to base 10

[JackDavidson]

This is an alternate option to my other pull request. This simply changes the indexing literals/constants to base 10 for improved readability and better compatibility with verilator.

a change might be, for example:

assign xyz = somewire[2'h3:1'h0]; assign xyz = somewire[3:0]; // <= to this

see also: https://github.com/ucb-bar/chisel/pull/679

only this pull or the other one should be accepted

[ghost]

Can one of the admins verify this patch?

[ucbjrl]

ok to test