Used the timer trick to continue reading when user stays idle

http://vim.wikia.com/wiki/Timer_to_execute_commands_periodically
Added a shell buffer.

Currently only for GDB
Added keymap for clearing all the breakpoints
Added shell buffer support for PDB
Added shell buffer support for rdebug

Also made it skip stops at external files
Merge branch 'master' of github.com:someboddy/vim-vebugger

 necessary,