message: support inserting outside code when texts are selected, some like VS
  that will be useful for user to insert snippet from cmd palette `insert snippet` if user select some text for surronding
diff: "body": [
  "checked",
  "{",
  - " $0",
  + " ${TM_SELECTED_TEXT}$0",
  "}"
  ],
  "description": "Checked block"
  "Console.WriteLine": {
  "prefix": "cw",
  "body": [
  - "System.Console.WriteLine($0);"
  + "System.Console.WriteLine(${TM_SELECTED_TEXT}$0);"
  ],
  "description": "Console.WriteLine"
  },
  "body": [
  "do",
  "{",
  - " $0",
  + " ${TM_SELECTED_TEXT}$0",
  "} while (${1:true});"
  ],
  "description": "do...while loop"
  "body": [
  "else",
  "{",
  - " $0",
  + " ${TM_SELECTED_TEXT}$0",
  "}"
  ],
  "description": "Else statement"
  "body": [
  "foreach (${1:var} ${2:item} in ${3:collection})",
  "{",
  - " $0",
  + " ${TM_SELECTED_TEXT}$0",
  "}"
  ],
  "description": "Foreach statement"
  "body": [
  "for (int ${1:i} = ${2:length} - 1; ${1:i} >= 0 ; ${1:i}--)",
  "{",
  - " $0",
  + " ${TM_SELECTED_TEXT}$0",
  "}"
  ],
  "description": "Reverse for loop"
  "body": [
  "for (int ${1:i} = 0; ${1:i} < ${2:length}; ${1:i}++)",
  "{",
  - " $0",
  + " ${TM_SELECTED_TEXT}$0",
  "}"
  ],
  "description": "for loop"
  "body": [
  "if (${1:true})",
  "{",
  - " $0",
  + " ${TM_SELECTED_TEXT}$0",
  "}"
  ],
  "description": "if statement"
  "body": [
  "lock (${1:this})",
  "{",
  - " $0",
  + " ${TM_SELECTED_TEXT}$0",
  "}"
  ],
  "description": "Lock statement"
  "prefix": "ifd",
  "body": [
  "#if ${1:true}",
  - " $0",
  + " ${TM_SELECTED_TEXT}$0",
  "#endif"
  ],
  "description": "#if"
  "prefix": "region",
  "body": [
  "#region ${1:Name}",
  - " $0",
  + " ${TM_SELECTED_TEXT}$0",
  "#endregion"
  ],
  "description": "#region"
  "body": [
  "try",
  "{",
  - " $1",
  + " ${TM_SELECTED_TEXT}$1",
  "}",
  "finally",
  "{",
  "body": [
  "try",
  "{",
  - " $1",
  + " ${TM_SELECTED_TEXT}$1",
  "}",
  "catch (${2:System.Exception})",
  "{",
  "body": [
  "unchecked",
  "{",
  - " $0",
  + " ${TM_SELECTED_TEXT}$0",
  "}"
  ],
  "description": "Unchecked block"
  "body": [
  "unsafe",
  "{",
  - " $0",
  + " ${TM_SELECTED_TEXT}$0",
  "}"
  ],
  "description": "Unsafe statement"
  "body": [
  "using (${1:resource})",
  "{",
  - " $0",
  + " ${TM_SELECTED_TEXT}$0",
  "}"
  ],
  "description": "Using statement"
  "body": [
  "while (${1:true})",
  "{",
  - " $0",
  + " ${TM_SELECTED_TEXT}$0",
  "}"
  ],
  "description": "While loop"
  