Improved handling of text for the PS driver. Now pass the text bounding box values in the RBUF array for the IFUNC=31 option. These are calculated in GRTEXT where the only special case required for PS drivers is not to call GRLIN0 to actually plot the lines. This is much simpler than the previous method of setting the color to the special value of -1.
Also moved the PS driver-specific code related to the PS_VERBOSE_TEXT environment variable (which is obsolete) from GRTEXT into PSDRIV and reformatted and renamed the subroutines in PSDRIV to conform better to PGPLOT standards.