Fix: Syntax highlighting for various issues (#2810)

* highlighter: Fix region & pattern detection

* syntax/sh: Highlight upper case options too

* syntax/c(pp): Try to synchronize the rules to lower the maintenance effort

* syntax/ruby: Fix explicit filename detection in directories

* highlighter: Respect skip rules in regions

* syntax/sh: Fix parameter expansion, cond. flags and generalize filename via ""

* syntax/php|vi: Correct strings in comments to comments only

Additionally improve vimscript comment handling.

* highlighter: Remove problematic start|end check in find(all)Index()

...and additionally remove recursive region end detection

runtime/syntax/javascript.yaml

@@ -10,12 +10,7 @@ rules:
     - constant.number: "\\b[-+]?([0-9]+[EePp][+-]?[0-9]+)[fFlL]?"
     #- identifier: "[A-Za-z_][A-Za-z0-9_]*[[:space:]]*[(]"
     # ^ this is not correct usage of the identifier color
-    - symbol.brackets: "(\\{|\\})"
-    - symbol.brackets: "(\\(|\\))"
-    - symbol.brackets: "(\\[|\\])"
-    - symbol.brackets: "(\\{|\\})"
-    - symbol.brackets: "(\\(|\\))"
-    - symbol.brackets: "(\\[|\\])"
+    - symbol.brackets: "[(){}]|\\[|\\]"
     - symbol.operator: "([-+/*=<>!~%?:&|]|[.]{3})"
     - statement: "\\b(async|await|break|case|catch|const|continue|debugger|default)\\b"
     - statement: "\\b(delete|do|else|export|finally|for|function\\*?|class|extends)\\b"
@@ -73,7 +68,9 @@ rules:
     - comment:
         start: "/\\*"
         end: "\\*/"
+        skip: "\\\\."
         rules:
+            - constant.specialChar: "\\\\."
             # function documentation
             - identifier: "\\s\\*\\s.*"
             - todo: "(TODO|XXX|FIXME)"