Some appearance tweaks

Signed-off-by: Diep Pham Van <imeo@favadi.com>
Revert "Some appearance tweaks"

This reverts commit 58c0a9a0525aa78461ad80f54d16cbcf59a1f850.
Change to dark background and Consolas font
Add honza snippets

Snippets have removed from ultisnips
Add gnuplot