Squashed commit of the following:

commit a83d75aed2fae9e0ae877642fbbd8e82b6bacca6
Author: lyao2 <lyao2@LYAO2-WS01.cisco.com>
Date:   Fri Apr 4 15:40:54 2014 +0800

    check makefile

commit 097bd858ef46b6febda098253cc0d48e2eb0c95c
Author: lyao2 <lyao2@LYAO2-WS01.cisco.com>
Date:   Fri Apr 4 09:43:24 2014 +0800

    add mask flag

commit 34e86276000bac158abdfb839b1a5aaebac1e235
add scroll detection files
add interface for error concealment, to be continued
correct formatted file headers
Remove the unused WELSVP_EXPORTS define
Merge pull request #651 from mstorsjo/remove-unused-define

Remove the unused WELSVP_EXPORTS define
remove m_pScrPicList, which is not needed anymore
fix colorsapce check
refine method EncodeFrame
Merge pull request #653 from volvet/fix_colorspace_check

fix colorsapce check
Merge pull request #655 from huili2/EC_interface

add interface for error concealment, to be continued
Merge pull request #654 from volvet/refine_enc_frame

refine method EncodeFrame
refine decoder side intrapred unit test, test assembly routine
only when the cpu feature can support it
Merge pull request #656 from licaiguo/refine-dec-intrapred-ut

refine decoder side intrapred unit test, test assembly routine only when the cpu feature can support it
Merge pull request #635 from lyao2/new_scroll_dev

add scroll detection files
Merge pull request #652 from volvet/refine_enc_wrap

remove m_pScrPicList, which is not needed anymore