Refactors history and how the database is stored

[yurydelendik]

• Alternative for https://bugzilla.mozilla.org/show_bug.cgi?id=986966 and https://bugzilla.mozilla.org/show_bug.cgi?id=865893
• Moves localStorage checks to the compatibility.js

Pros:

• Firefox will not store any history of the browsed files permanently, so no keeping of the trail

Cons:

• Firefox will not store any history of the browsed files permanently, so no restore of the current PDF position after browser is closed

[Snuffleupagus]

so no restore of the current PDF position after browser is closed

Unless you choose to save the current tabs on exit, because in this case the browsing history should provide this functionality.

Edit: That doesn't actually appear to be working as I thought, so please ignore the comment above.

[Snuffleupagus]

Left-over from debugging?

[yurydelendik]

thanks

[brendandahl]

Works for me. @Mossop Any review comments?

[Mossop]

Looks fine