Implement history navigator(#14)
Merge pull request #15 from syohex/support-history

Implement history navigator(#14)
Update document

 - add explanation of helm-gtags-next-history and helm-gtags-previous-history.
 - remove old information
 - fix sample configuration based on package.el or el-get
Add message about GNU global version
Bump up version and update Changes
Support GTAGSLIBPATH(#13)

Use previous context stack if current path is under GTAGSLIBPATH,
and create new context stack if previous context stack in such case
Fix overwrite tag location problem
Merge pull request #16 from syohex/support_libpath

Support libpath(#13)
Apply shell quote for file name(#17)
Bump up version and update Changes
Update document