App size (#146)
* avoid indexing to reduce binary size
use try call to avoid panic machinery to be added by the compiler
optimize for binary size and remove debug symbols
* update tests
* bump app version and update snapshots
* Derive Debug only under test
* Remove panic-halt to reduce app size
* Reduce calls to procedures that can cause panics
* Rename LedgerPanic to ApduPanic
* fix format
* use unreachable_unchecked
* some improvements in size
* fix return value
* Update zxlib
* use copy_from_slice and better error report
