Added dw_pixmap_get_width() and dw_pixmap_get_height() by request for language bindings. These APIs function identical to the already existing DW_PIXMAP_HEIGHT/WIDTH() macros. The macros will exist at least until the end of the 3.x series, at which point they may be retired.

# Set these here to change the version for all platforms
DW_MAJOR_VERSION=3
DW_MINOR_VERSION=3