add undocumented libs

[macMikey]

in ali's session on x-platform widget creation, he has some use lines that don't seem to appear, anywhere

use com.livecode.widget.native.button.android
use com.livecode.widget.native.button.ios
use com.livecode.widget.native.button.mac
use com.livecode.widget.native.button.linux
use com.livecode.widget.native.button.emscripten
use com.livecode.widget.native.button.shared

[macMikey]

After Ralph's question #36, we have discovered that some of the more standard libraries (e.g. com.livecode.library.iconsvg) don't appear, either, and probably should be included.