[iso] add dumping of ISOs from optical media (Alt-O)

[loc] complete Hebrew translation

* Closes pbatard#204

[loc] add Hebrew translation (incomplete)

[loc] fix license display for RTL languages

[bb] fix rand() initialization

* What do you know, srand() is thread-local...

[misc] add an indication in the log for portable mode

* Closes pbatard#854

[misc] Linux cross compilation fixes

* Closes pbatard#850

[internal] update issue template

[loc] fix a typo in German translation

[loc] update Latvian translation