[Ohrrpgce] SVN: teeemcee/10828 gfx_sdl2: set various hints, other gfx_sdl2_init improvements, and fix g

[subversion at HamsterRepublic.com]

teeemcee
2018-10-31 05:28:00 -0700 (Wed, 31 Oct 2018)
317
gfx_sdl2: set various hints, other gfx_sdl2_init improvements, and fix gfx_sdl2_recenter_window_hint

I simply read through the list of hints and picked those that I wanted.

Strangely, although gfx_sdl2_recenter_window_hint was totally wrong before,
there doesn't seem to be any change in behaviour: it mostly works?
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U   wip/gfx_sdl2.bas