Remove downloaded file in case of errors (e.g. wrong checksum)
Fix download info text being cut off

Not sure why, but this seems to fix #181.
Add known issue for Huawei and Nubia ROMs
Use dark background for application startup

This does NOT change the default theme. However, it's probably more
acceptable to switch from dark to light background than the other way
round, because it's not "blinding" the user.

The alternative would be a transparent background (only the action bar
showing up), but it doesn't look better in my eyes.

Fixes #180
Use darker cards for black theme
bin v58
Translation updates

Changes were contributed by:
  [bg] Stefan Stefanov (closes #175)
  [es] juaoose, David Vaz Guijarro (closes #179)
  [fr] desalesouche (closes #176)
  [th] ecxst (closes #174)
Bump version to 2.6.1