Use signed values since these can be used for negative values as well.
Use our own kill function in order to avoid kill(-1), and rework killing in check_children.

check_children now utilizes stop_child in order to kill child
processes in order to reuse the same logic used elsewhere.
Increase Shutdown timeout in exec app definition.
Whitespace fixes - tab to spaces.
Accept options for manage command.
Merge branch 'manage' into make_mac_compile_hack
Merge branch 'stop_child_fix' into make_mac_compile_hack

Conflicts:
	src/exec_app.erl