Rename error_print() to print_error()

Signed-off-by: Vladimir Petukhov <kavinator@gmail.com>
Rename debug_print() to print_debug()

Signed-off-by: Vladimir Petukhov <kavinator@gmail.com>
Merge branch 'rename-functions' into dev-v0.6

* rename-functions:
  Rename debug_print() to print_debug()
  Rename error_print() to print_error()