Achieve in a new way

README: Achieve in a new way.

• in gl-journal.c remove cursor_current.only use a cursor. because a single "append" signal can indicate one or more newly added entries add while to solve it.
• in gl-ournal-modle.c should free the entries firstly.

I am very sorry that I didn't make a good progress.

1. the information of sd_journal is too little.
2. I don't understand the doc sd_journal clearly.

for example, I am not sure if sd_journal_next/previous() move after sd_journal_seek_tail/head.

About initialize of cursor_last ,maybe it is not a good way which I useed . If you have some suggestion,please tell me.

And the problem I met,

• it seems need to free something in on_new_entry_added(), because when I choose another "catagorylist", it will not refresh the model . also dispaly those entries which are in the last categorylist" I try to free query(maybe).

THX in advanced!