Added initial support for output to SVG image format

[miilic]

Try it with commands like
./map_generation -v --with-svg
or
./map_generation -v --with-svg --svg-colors
It should produce both output.png and output.svg files, which you can then examine using your SVG editor of choice.

[rlguy]

Hi miilic,

This looks like a great feature, thank you! I'll test it out and merge it with the master branch when I have some free time.

Best Regards,
Ryan

[cprevoe]

As I just did a rudimentary version of the same thing as @miilic, I +1 this feature. I can confirm that built and ran it myself and it does work. I've not done more than a cursory look at the code though.