#192 Store bookmark as soon as it's created

[Daniel Bedrenko]

It would be great if when a bookmark is created, this is immediately saved to storage. It's very annoying that if my OS crashes for whatever reason, like power is accidentally cut, that all my annotations have been wiped out!

This is the case currently with v3.1.2-52

Thanks for the great software, it is my go-to reader for ebooks.