Partial revert for addr switches, instead always use offsets
Patch mkbootimg:
- change *addr back to *_offset since this wasn't reverted properly before anyway
- possible fix for dtb support where an additional pagesize of data/padding beyond dt_size was missing

Patch unpackbootimg:
- export *off files instead of *addr
- add support for kernel_offset
- possible fix for dtb support by splitting with an additional pagesize of data/padding beyond dt_size

Update .gitignore:
- add proper exclusions for Makefile products