Import the sourceforge wiki

[lazka]

All pages from https://sourceforge.net/p/mingw-w64/wiki2/browse_pages/ converted to markdown with pandoc.

I tried to avoid making any content changes, except for internal links, and I added some subdirectories for related pages.

Everything in "misc" wasn't reachable from the "home" page, only via the search or page list.

Why:

• Have one place for the documentation
• Better UX then the sourceforge wiki for end users (tree structure, interactive search)
• It's easier to change for outside contributors
• Potential changes can be reviewed
• Changes are in git and it's less scary to just delete things

Next steps after merging: clean things up

Here is how this looks like right now:

[lazka]

On IRC there was the preference expressed to continue maintaining the documentation on Sourceforge, so I'm closing this.

If this changes in the future, feel free to ping me.