EP128: Use texture locking mode, instead of updating texture (slower)

[lgblgblgb]

No description provided.

[lgblgblgb]

Also, clear render target may be not needed at all, only in the case if target changed its size, ie resizing, full screen event, etc. These (with the locking as well) may not mean too much on a PC, but probably it matters on a low-end hardware like raspberry pi.

[lgblgblgb]

It's questionable ... With my Commodore VIC20 and 65 emulators I couldn't see too much difference even not on a Raspberry Pi model 1. Moreover, using locked texture makes it harder to pause the emulation and show "partly" rendered frames etc ...

[lgblgblgb]

This is done already within the Xemu project, so closing it. Note, though it must be checked if ep128 target within the Xemu project really integrates Xemu features well enough, still there are many old implementations, private to ep128 target only, which is BAD. See: #197

[lgblgblgb]

Note: EP128 target within Xemu still use texture update! But in general, locked textures are OK now, just the EP128 target should be modified at some point!