A couple of features and bug fixes

Hello there,
I have been testing out Lychee fixing bugs and adding minor features in progress. Here is a list of  the changes I have introduced so far. 

* Faster photo browsing thanks to caching.
* Default sort order of albums is changed from new to old.
* Preserves scroll position when changing from albums to album and vice versa
* Better Unicode support for values read from the database

Hopefully these are of use to you. If you have any questions, do not hesitate to ask.

Cheers,
Roman
A new PR including the other changes would be nice.