Don't test -D option(pipe mode) in wine environment
Fix pipe-mode test for mingw build
Separate convert_sixel into 3 functions
Add tests for applying vt340 built-in palette
Search a next node from nodes after a current node instead of context->node_top in sixel_encode_body().
Merge branch 'arakiken' of github.com:saitoha/libsixel into arakiken