Vendor selectionhighlight, bracketmatch, colorpreview, navigate, editorconfig (2.1.8-7)

Five more plugins from lite-xl-plugins @ 31eef29, all default VSCode
behaviors:

- selectionhighlight: highlights other occurrences of the selected word
- bracketmatch: highlights the bracket matching the one under the cursor
- colorpreview: inline swatches for #hex/rgb()/hsl() color literals
- navigate: Go Back / Go Forward cursor history (alt+left/right)
- editorconfig: applies .editorconfig files; vendored as the whole
  upstream directory (parser + test harness, lite-xl test editorconfig);
  builds on the bundled trimwhitespace plugin

All depend on core only (editorconfig additionally on trimwhitespace,
already shipped). Verified against the built package: all plugins load,
navigate registers its commands, and an .editorconfig with
indent_size = 2 is applied to an opened file.

Pinned to lite-xl-plugins @ 31eef29 (see debian/extra/README.source).

debian/extra/plugins/editorconfig/tests/parser/comments.in

@@ -0,0 +1,47 @@
+; test comments
+
+root = true
+
+[test3.c]
+; Comment before properties ignored
+key=value
+
+[test4.c]
+key1=value1
+; Comment between properties ignored
+key2=value2
+
+; Semicolon or hash at end of value read as part of value
+[test5.c]
+key1=value; not comment
+key2=value # not comment
+
+; Backslash before a semicolon or hash is part of the value
+[test6.c]
+key1=value \; not comment
+key2=value \# not comment
+
+; Escaped semicolon in section name
+[test\;.c]
+key=value
+
+[test9.c]
+# Comment before properties ignored
+key=value
+
+[test10.c]
+key1=value1
+# Comment between properties ignored
+key2=value2
+
+# Octothorpe at end of value read as part of value
+[test11.c]
+key=value# not comment
+
+# Escaped octothorpe in value
+[test12.c]
+key=value \# not comment
+
+# Escaped octothorpe in section name
+[test\#.c]
+key=value