changelog:
======================
* Move goproject properties to project resource folder, not '.metadata'
folder and change name to '.goproject'
* Fix the problem which not gopath showing in project explorer view when
you have more than one folder for gopath setting in preference. And when
you have duplicated path with goroot folder in gopath, and it would not
showing in project explorer
+ Add a project based gopath setting page, you can add your need project
as gopath also include remove button
+ Add a project go build option, you can custom your own build flag
arguments
+ Add required gopath library into gocode