Improve verilog support, counts and repeat

[zegervdv]

This PR adds a couple of features and extensions:

• Improved verilog syntax: allows 28'hA83D, 12'd123 etc
• Add a count to the increment/decrement value: 7 on 123 results in 130
• Add optional repeat.vim support, so . will repeat the last increment/decrement (with count)

If you prefer I can split this into multiple PRs if you don't want to take in everything.