Debugger: support step-over and step-out commands

[ivan-mogilko]

Debugger (Editor) currently supports stepping line by line, strictly following script execution; that results in next break occuring inside nested function calls as well. But that's not always convenient in case of complex scripts.

I propose to add 2 more step commands:

1. Step-over means that it will not step inside called functions, but wait until next line in the current function is reached. (proposed hotkey is F10)
2. Step-out means that it will wait until current function returns, and breaks at the next line after its call. (proposed hotkey is Shift+F11)

I suppose this may be implemented either:

• by adding more options to handle by the engine; this seems to be better long term.
• or by using existing breakpoint mechanism in the editor, where editor would create a temporary hidden breakpoint in certain lines, and remove them when any break happens.

[ericoporto]

Supposedly we have

function Bar()
{
  // there is a breakpoint here
}

function Foo()
{
  int a = 2; // debug cursor is here
  Bar();
  int b = 3;
}

A step over would then step over Bar or in this case that we set a breakpoint inside it would stop at that breakpoint (like if we had hit the "continue" like button)?

[ivan-mogilko]

It should break at the next found breakpoint along the execution, whether it's user's breakpoint or one added by another command. Yes, it must be consistent with "continue".

[ivan-mogilko]

In regards to implementation:
breaking is currently handled in this function in the engine:

ags/Engine/debug/debug.cpp

Lines 632 to 633 in de288ad

	// allow LShift to single-step, RShift to pause flow
	void scriptDebugHook (ccInstance *ccinst, int linenum) {

The variables that control behavior are:
breakpoints - array of breakpoints
break_on_next_script_step - tells to break at next execution step.

I suppose that these may be amended with more instructions. The question is mostly in which conditions to use for making a break.