Support continue with a count

[TamaMcGlinn]

This SO answer illustrates gdb's ability to let you skip a breakpoint some number of times:

(gdb) c 5
Will ignore next 4 crossings of breakpoint 2.  Continuing.
1
2
3
4
5

Breakpoint 2, main () at main.c:6
6               i++; /* Line 6 */

We can currently achieve this by doing VGBrawWrite and entering the c 5 as above. It would be nice to make this a bit vimmier by allowing a count to be specified before the continue command.