TracTimeline navigation fixes:  - use the request's timezone for defining 'today' (#4758)  - keep the current ''daysback'' parameter in the navigation links  - fix the check for the ''Next period'' link (#4757)
TracTimeline navigation fixes:
 - use the request's timezone for defining 'today' (#4758)
 - keep the current ''daysback'' parameter in the navigation links
 - fix the check for the ''Next period'' link (#4757)

Thanks to Sergei Haller for reporting those issues and providing a patch for #4757.

git-svn-id: eda3d06fcef731589ace1b284159cead3416df9b@4765 af82e41b-90c4-0310-8c96-b1721e28e2e2

jun66j5/trac-ja,walty8/trac,walty8/trac,walty8/trac,jun66j5/trac-ja,netjunki/trac-Pygit2,netjunki/trac-Pygit2,jun66j5/trac-ja,jun66j5/trac-ja,netjunki/trac-Pygit2,walty8/trac