Code that adds and deletes breakpoints has been added but delete doesn't work yet. Refactoring and ghci output
parsing is needed (we need to save added breakpoint number to delete it later)
Line number converting code has been added
Docs for HaskellLineBreakpointHandler have been added
Changes in set/removeBreakpoint methods
Set breakpoint action now works, so we can set breakpoints before starting Debug process (by pressing Debug
 button), but can't remove them on debug running. However we can set and remove before debug process is
 started. Also, debug process correctly stops on set breakpoint.