Use new syntax highlighting engine from zyedidia/highlight

This changes all the syntax files in the runtime directory and also
changes how syntax highlighting is done from inside micro.

runtime/syntax/cpp.yaml

@@ -0,0 +1,51 @@
+filetype: c++
+
+detect:
+    filename: "(\\.c(c|pp|xx)$|\\.h(h|pp|xx)$|\\.ii?$|\\.(def)$)"
+
+rules:
+
+    - identifier: "\\b[A-Z_][0-9A-Z_]+\\b" 
+    - type: "\\b(auto|float|double|bool|char|int|short|long|sizeof|enum|void|static|const|constexpr|struct|union|typedef|extern|(un)?signed|inline)\\b"
+    - type: "\\b((s?size)|((u_?)?int(8|16|32|64|ptr)))_t\\b"
+    - statement: "\\b(class|namespace|template|public|protected|private|typename|this|friend|virtual|using|mutable|volatile|register|explicit)\\b"
+    - statement: "\\b(for|if|while|do|else|case|default|switch)\\b"
+    - statement: "\\b(try|throw|catch|operator|new|delete)\\b"
+    - statement: "\\b(goto|continue|break|return)\\b"
+    - preproc: "^[[:space:]]*#[[:space:]]*(define|pragma|include|(un|ifn?)def|endif|el(if|se)|if|warning|error)"
+    - constant: "('([^'\\\\]|(\\\\[\"'abfnrtv\\\\]))'|'\\\\(([0-3]?[0-7]{1,2}))'|'\\\\x[0-9A-Fa-f]{1,2}')"
+
+      ##
+      ## GCC builtins
+    - statement: "(__attribute__[[:space:]]*\\(\\([^)]*\\)\\)|__(aligned|asm|builtin|hidden|inline|packed|restrict|section|typeof|weak)__)"
+
+      #Operator Color
+    - statement: "([.:;,+*|=!\\%]|<|>|/|-|&)" 
+
+    - constant.number: "(\\b[0-9]+\\b|\\b0x[0-9A-Fa-f]+\\b)"
+    - constant.number: "(\\b(true|false)\\b|NULL)"
+
+    - constant.string:
+        start: "\""
+        end: "\""
+        rules:
+            - constant.specialChar: "\\\\."
+
+    - constant.string:
+        start: "'"
+        end: "'"
+        rules:
+            - preproc: "..+"
+            - constant.specialChar: "\\\\."
+
+    - comment:
+        start: "//"
+        end: "$"
+        rules:
+            - todo: "(TODO|XXX|FIXME):?"
+
+    - comment:
+        start: "/\\*"
+        end: "\\*/"
+        rules:
+            - todo: "(TODO|XXX|FIXME):?"