Update README.txt for Drupal 7.x-2.x branch

feel free to reopen this when bug still hosts at latest dev

I'm surprised that this very important module doesn't have any documentation or screencast in the Drupal project page and I'm pretty sure that mastermindg is searching for that too, not posting some bugs.
Any additional info will be very useful for everybody who starts this module.

I rewrote the contents of the README.txt to update it to Drupal 7. Changes:

• I wrapped all the lines at 80 characters, as is done in most contrib modules and all of Drupal core. I couldn't find an official standard on this but I think it increases readability signicantly.
• Updated all paths, URLs, and navigation paths to match actual locations in D7.
• Updated installation instructions (after I went through it myself) for GMap API V3.
• Changed "input format" to "text format" everywhere, per D7 terminology.
• Replaced the "XHTML" section with "Quirks mode", since Google now recommends HTML5 doctypes OR XHTML doctypes.
• Added a huge section on Views integration.
• Removed the credits. If someone wants to update this instead, please do so, but we have had significantly larger contributions that aren't mentioned here and very minor (or completely irrelevant to the 7.x-2.x branch) contributions listed. I thought it best to just remove the whole thing.

Attached as both a patch or just the whole README.txt, which might be easier to work with and review.

Thank you Nathan!

I really appreciate the time you spent on this. Despite the fact that I've been using the module for long enough to know my way around, still the README is a valuable asset to run to each time something is unclear. I hope with it in place there'll now be less support requests in the queue and that in turn will give the maintainers more time to devote on actual code writing.

Thanx once again ;)

#3 commited pushed to 7.x-2.x
Thanks a lot for Your work @quicksketch

Thanks @podarok! You made my night. :)