gles2rice: Removed superfluous changes to Config class.

The windowXpos and windowYpos configuration settings are not being
used presently.  The windowHeight and windowWidth settings seem to
duplicate the functionality already provided by VIWidth and VIHeight
in the upstream version.  Removing these elements does not seem to
make a difference in any of my tests (including Super Mario 64).  If I
am missing something, please let me know.

If Mario 64 and the others need their height re-scaled, I suggest that
we revisit the topic after upstream synchronization.  If the changes
are indeed necessary, then I'm sure the upstream community will
appreciate them.  Right now I do not see any impact in removing them
anyhow.
front: Place non-default rice settings in config file.

These values were hard-coded into the gles2rice defaults.  Moving them
here allows gles2rice to retain its upstream config.
gles2rice: Revert default config params to upstream values.

Android-specific defaults should be specified in the configuration file
rather than hard-coded into the plugin.  See previous commit.