Here's a new version.
This version does not contain any new functionality (except for a tiny bugfix which affects the renaming of collections).
So, why has the version been bumped to 1.4.0? Simple: because internally, pretty much everything has changed. All of the code has been completely refactored, to even prepare it for Paperwhite support. If you're curious, here is the massive changeset
There are major differences between Firmware version 5.1.2 and 5.2.0 (thanks, Amazon, for getting ever more aggressive with the code obfuscation!
Note that it still doesn't support the Paperwhite - I have only laid the groundwork for the support, by separating the device-independent from the device-dependent parts. The device-dependent part for 5.2.0 still needs to be done - and this will be some tough work.
Anyway, because of these major code changes, I may well have introduced a few new bugs (well, I don't hope so, but you never know). So please install the new version and let me know if everything works correctly, or if maybe I actually did break something.