fix mahler markdown some more

saw you'd started it so thought i'd finish it off, picture and caption still need doing. also i removed the hover text for the text links i hope that's ok.
With urls pointing to other posts, could you please:
* change the filename of the post it references so that it has a nice url? That is, there should be a file in `_posts` called `2013-xx-xx-symphonyspring.markdown`. Could you change it so that words have hyphens in between them, and the url better reflects the title? In this case `2013-xx-xx-symphony-spring-concert.markdown` would do
* change the url to a relative one pointing to that same post on the new site, so here it would be `/blog/2013/symphony-spring-concert`