fix compilation error with later 3.0.x versions of arduino-esp32

[jscrane]

This fixes a compilation error in VGA.h:

/home/steve/Arduino/libraries/ESP32Lib/src/VGA/VGA.h: In member function 'virtual bool VGA::init(const Mode&, const int*, int, int)':
/home/steve/Arduino/libraries/ESP32Lib/src/VGA/VGA.h:36:10: error: no return statement in function returning non-void [-Werror=return-type]
   36 |         {}

It looks as if this became an error sometime between version 3.0.3 and 3.0.7.

I'm also getting a lot of compiler warnings. I can have a go at fixing these as well if you'd like?

Cheers,
Steve

[jscrane]

The second commit addresses a probable bug which would have always caused a buffer allocation.

[otiskujawa]

Thanks
This fixes #98 and #97 therefore making 4.0 usable again