Added skeleton for the preferences code
Updated Hungarian Help translation.
Merge branch 'help'
Added skeleton for the preferences code
Merge branch 'settings' of github.com:gergelypolonkai/astrognome into settings
Updated for SWE-GLib 2.0 API
Make get_by_xpath() string return value a maybe-string
Remove references and calls to libgd in favour of Gtk 3.10 calls
Fix typo in chart XSL
Update README.md with some up-to-date  information
Remove unnecessary gswe_planet_data_unref() calls

This introduced an ugly bug when changing from the Edit tab to Chart view
for the second time.
Add .a files to .gitignore
Move ag_window_redraw_chart() to a more appropriate place
Change deprecated GTK stock items to actual values
Add message dialogs to indicate save errors
Set southern latitude/western longitude if saved chart has negative values

Fix #16
Update po file for Hungarian translation
Add Hungarian translation for new error messages
Add timezone control to edit tab

Fix #15
Add GTK message dialogs instead of g_warning() calls.

This is to enhance UX. Fix #9