Remove stub interfaces for hw decoding

There is no implementation available for actually doing decoding
in HW.
Merge pull request #286 from mstorsjo/remove-hw-decode

Remove stub interfaces for hw decoding
name pre-process steps
remove unused temporal ID info in decoder API
Merge pull request #291 from volvet/name_process_step

give right name to pre-process step1 and step3
    encoder interface update step1
Merge pull request #293 from ruil2/interface_step1

    encoder interface update step1 --- review request #75
Merge pull request #295 from huili2/dec_api_rm_tl

remove unused temporal ID info in decoder API
update to the last commit: interface change