* slideshow.js: changed default slide interval to 45s from 30s. May fix lp:423639, but not directly marked because it is still uncertain.
* Slideshow.py: now loads slides from correct place in build directory by default (previously loaded from ./slides, which is no longer organized like the build directory)
* generate-local-slides.sh: "directory = new Object();" is added to directory.js again. This is necessary for the script to cooperate.