* Replace unneeded gtkopacity with transparentize
* gtk3: Remove unneeded color variable
Budgie theming added a new variable to _colors.scss that was only
used at one spot. Replace it with white, which makes more sense since
other panel elements are white as well.
* feat(render_assets): optional support for resvg
* refactor: rename MENU_BG to HDR_BG and MENU_FG to HDR_FG (and migrate old values on runtime)
* fix(configure): allow to run if inkscape not installed but resvg does
* feat(makefile): make optipng optional
* fix symlinks after sedding
* fix(configure): allow to run if inkscape not installed but resvg does - 2
* style: shellcheck all .sh files
* fix(autogen.sh): remove redundant escaping
* fix(*: makefile: rendersvg): use --zoom 2 to workaround --dpi problem