Attempt to change to root dir before executing python script

When inside a git repo, attempt to change to the root dir
before running python script. Prevents a bunch of errors
when mktargets.sh is executed from the wrong dir.
Merge pull request #588 from varunbpatil/root_dir

Attempt to change to root dir before executing python script
Remove an unnecessary 'cd' in the mktargets.sh script

There's no need to return to the original directory at the end of
a script - the current working directory within the subshell that
executes the script doesn't affect the working directory in the
calling shell.
Merge pull request #589 from mstorsjo/simplify-script

Remove an unnecessary 'cd' in the mktargets.sh script
add function pointer
Merge pull request #591 from sijchen/me_merge91

[Encoder ME] add function pointer initialization
    add preprocessing parameter for screen content
Merge pull request #592 from ruil2/enc_processing

    add preprocessing parameter for screen content
add ExpandPic encoder unit test
Merge pull request #593 from ganyangbbl/encUT_ExpandPic3

add ExpandPic encoder unit test file
Add feature search basic functions
    add scene change detection in workflow for screen content
Merge pull request #596 from ruil2/enc_processing

    add scene change detection in workflow for screen content
Remove compiler warnings
Merge pull request #595 from sijchen/fme_merge12

[Encoder ME] Add feature search basic functions
add layer sps/pps to decoder context
Merge pull request #599 from licaiguo/add-sps-pps-for-each-layer

add layer sps/pps to decoder context
add usagetype setting for screen content
fix ios encDemo build
Merge pull request #601 from volvet/fix-ios-build

fix ios encDemo build