[mod] simple theme: use sharp instead of convert to create .png from .svg

define a custom grunt task, since grunt-sharp is too old (it can't be installed).
in gruntfile.js, the image tasks are moved at the end the build chain.

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

manage

@@ -708,42 +708,12 @@ themes.oscar() {
 themes.simple() {
     local static="searx/static/themes/simple"
     (   set -e
-        convert_if_newer "src/brand/searxng-wordmark.svg" "$static/img/favicon.png" \
-                         -transparent white -resize 64x64
         build_msg GRUNT "theme: simple"
         npm --prefix searx/static/themes/simple run build
     )
     dump_return $?
 }
 
-convert_if_newer() {
-
-    # usage: convert_if_newer <origfile> <outfile> [<options>, ...]
-    #
-    #    convert_if_newer "path/to/origin.svg" "path/to/converted.png" -resize 100x100
-    #
-    # Run's ImageMagik' convert comand to generate <outfile> from <origfile>, if
-    # <origfile> is newer than <outfile>.  The command line is to convert is::
-    #
-    #    convert <origfile> [<options>, ...] <outfile>
-
-    local src_file="$1" && shift
-    local dst_file="$1" && shift
-
-    if [[ "${src_file}" -nt "${dst_file}" ]]; then
-        if ! required_commands convert; then
-            info_msg "to install build tools use::"
-            info_msg "   sudo -H ./utils/searx.sh install buildhost"
-            die 1 "install needed build tools first"
-        fi
-        build_msg CONVERT "${src_file}" "$@" "${dst_file}"
-        convert "${src_file}" "$@" "${dst_file}"
-    else
-        build_msg CONVERT "${dst_file} (up-to-date)"
-    fi
-}
-
-
 PYLINT_FILES=()
 while IFS= read -r line; do
    PYLINT_FILES+=("$line")