- "env ask", "env grep" and "setexpr" are needed for commissioning
- add support for ext4 file systems
- adjust default environment to use ext4 commands
- add write support for (V)FAT and EXT4
- add bitmap and splashscreen support
- print timestamp information for images

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Stefano Babic <sbabic@denx.de>