Fix and improve caping max level to player stage dimensions

- now the stage dimensions are properly detected through stageWidth & stageHeight properties
- capping is now based on two dimensions width and height
- if the stage size was changed during the playback the autoswitching will now consider new max_level value to switch up or switch down the stream level (no matter if the bandwidth was changed)
- the autoswitching mechanisms are runed only if the stream has more than 1 level
- HLSMaxLevelCappingMode enum class defines two possible max leve capping modes:
	- HLSMaxLevelCappingMode.DOWNSCALE - max capped level should be the one with the dimensions equal or greater than the stage dimensions (so the video will be downscaled)
	- HLSMaxLevelCappingMode.UPSCALE - max capped level should be the one with the dimensions equal or lower than the stage dimensions (so the video will be upscaled)

related to #165

Conflicts:
	src/org/mangui/HLS/streaming/AutoLevelManager.as 
(dimensions of stage and levels could be Numbers so it's not a good practice to make them int)
@aneebq I'll not be arguing about strict equals and their "mandatory" use in ActionScript 3 and the differences between the JavaScript and ActionScript 3 in this case - it's not the place for that. But even in JavaScript in this case, when we are comparing strings, there are no differences between `==` and `===`. We can't fall into the type casting scenario in this situation. Enough said. 

Switch-case is not needed here also. If @mangui will be a fan of switch-case construction I'll change it.