Add SpinButtons for integer and floating point variables in ForceVariableDialog

it allows to change variable value using only mouse.

Fix non-marking as manually forced floating point variable if the value isn't integer

For example, if user in debug variable panel set any floating point
variable to 34.3, then it's not shown as forced (blue color) and user
can't release this enforcement.

If user changes the value to 34.0, then enforcement shows
correctly. This is done because binary representation of floating point
numbers in IDE and runtime can be slightly different (double vs float)
and as a result values aren't equal.

Don't close ForceVariableDialog if user entered wrong new value

return back to edit field in this case