Add website source

[wbnns]

Closes #71.

Notes:

• opengeode.net is currently forwarding to http://taste.tuxfamily.org/wiki/index.php?title=Technical_topic:_OpenGEODE%2C_an_SDL_editor_for_TASTE - this redirect should be updated to https://taste.tuxfamily.org/wiki/index.php?title=Technical_topic:_OpenGEODE%2C_an_SDL_editor_for_TASTE (an https:// prefix at the beginning instead of just an http://) to ensure that visitors don't see an insecure website notification[1][2]. Updating to https will remove it[3][4].
• I can drop 6eb2aed and just point the README to the https version of the wiki page if that would be easier than having to mess around with the redirect (since the wiki is where a user would end up anyway at present).
• I also included 47b4923 in this PR, which isn't directly related to the website content. When updating the README, I noted there were a few places where it looked like there was some double-spacing (which did not seem to match the spacing preference of the rest of the document). Can drop this commit if it is intentional, or preferable to not include.
• The images from the wiki page have been added to wiki/images/. It looked like they could be further compressed without sacrificing quality (similarly to #70), so I went ahead and did that. They just need to be updated on the wiki to take advantage of the smaller file size. The appearance should still be the same.

Cc: @maxime-esa

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[maxime-esa]

Many thanks! I have edited the redirection to https, the process will take a bit of time during which the domains (opengeode.net and opengeode.org) are unavailable

[wbnns]

Thanks for the opportunity to contribute. Cheers!