Vendor raptor source files (was embedded gitlink)

Tree vendored at upstream 0019c5dd; origin + license recorded in
raptor/VENDOR.txt. Windows SDL dev packages excluded via .gitignore.

raptor/include/SDL2-devel-2.28.2-VC/SDL2-2.28.2/BUGS.txt

@@ -0,0 +1,16 @@
+
+Bugs are now managed in the SDL issue tracker, here:
+
+    https://github.com/libsdl-org/SDL/issues
+
+You may report bugs there, and search to see if a given issue has already
+ been reported, discussed, and maybe even fixed.
+
+
+You may also find help at the SDL forums/mailing list:
+
+    https://discourse.libsdl.org/
+
+Bug reports are welcome here, but we really appreciate if you use the issue
+ tracker, as bugs discussed on the mailing list may be forgotten or missed.
+