Suggestion: Tagging current version

[micclly]

I'll send a pull request which is for new MQL4 (which works only on MT4 build 600 or later).
This change break compatibility so new version of wrapper won't work on MT4 build 509 or earlier.
I suggest you to tag current version for users who use build 509 or earlier.
Tagged version will be available to download as zip from releases.