Update the reference of submodule plugin-x.
fixed ui layout clip
Update .travis.yml, Travis ci only builds 'v3' branch
[Jenkins][ci skip] Fix branch to v3 v2
Merge pull request #6385 from lmskater/change-develop-to-v3

[Jenkins][ci skip] Fix branch to v3 v2
Merge pull request #6386 from pipu/fixed_bug_ui_layout_clip

fixed the clipping of ui layout read from CocoStudio could not work
template work on IOS/Mac now
template for linux cpp
'develop' -> 'v3' branch for travis ci.
Merge pull request #6388 from dumganhar/travis-ci-build-fix

'develop' -> 'v3' branch for travis ci.
fixed compile fail
fixed return type is not right
Merge pull request #6390 from Dhilan007/v3

fixed compile fail on wp8
clean for kazmath in project file
Merge pull request #6391 from dabingnn/v3_optimize

V3 optimize
Merge pull request #6369 from natural-law/develop

Update the reference of submodule plugin-x.
Fix compile error for Lua
template work on wp8 now
Merge branch 'v3' of https://github.com/cocos2d/cocos2d-x into dev_compile_error
Merge pull request #6393 from Dhilan007/v3

template work on wp8 now