programs/dtwm/Dtwm.defs.src: Update default Dtwm backdrop
localized/*/app-defaults/Dtwm.tmsg: Update translations to reflect change
For CDE users with sufficiently high resolution screens, the abrupt
transition towards the end of the default SkyLight backdrop image bore
a close enough resemblance to graphical corruption to spur bug
reports. This problem likely did not manifest to the original CDE
developers using the typical monitors of the 1990s.
This patch changes the default backdrop to KnitLight, which comports
well with CDE's low distraction UI while still offering something
visually interesting enough to showcase CDE's support for bitmap
backdrops. Because of the repeating pattern within KnitLight, this
problem will not occur in the future. Additionally, SkyLight will be
retained as a CDE backdrop.