syntax: add support for textual EET representation

Eet can be manipulated via a textual representation, which looks like the
following:

  group "s_config" struct {
      value "version" uint: 0;
      value "font_size" uint: 12;
      value "font_name" string: "Mono";
      group "bg_color" struct {
          group "s_config_color" struct {
              value "r" uchar: 0;
              value "g" uchar: 0;
              value "b" uchar: 0;
              value "a" uchar: 255;
          }
      }
      value "use_bg_color" uchar: 0;
      value "mute_bell" uchar: 0;
  }

These changes allow vim to properly colorize textual eet files. The associated
file extension is ".eet".

ftdetect/eet.vim

@@ -0,0 +1,2 @@
+" Textual EET representation
+au BufRead,BufNewFile *.eet set filetype=eet

syntax/eet.vim

@@ -0,0 +1,28 @@
+" Vim syntax file
+" Language: EET
+"
+" This syntax file supports the textual representation of eet files. That is,
+" the output of `eet -d` (conversely, the input of `eet -i` and `eet -e`).
+" This is convenient when `vieet` is used.
+
+if version < 600
+  syntax clear
+elseif exists("b:current_syntax")
+  finish
+endif
+
+syn keyword eetSection group value key count
+syn keyword eetType struct array var_array list hash uint string uchar char
+syn keyword eetType short int long_long float double ushort ulong_long
+syn keyword eetType inlined
+syn keyword eetNull null
+syn match eetNumber display "\d\+"
+syn region eetString start=+L\="+ end=+"+
+
+hi def link eetSection Label
+hi def link eetType Type
+hi def link eetNumber Number
+hi def link eetString String
+hi def link eetNull Constant
+
+let b:current_syntax = "eet"