Rainlendar 2.10 Beta 118

# Changes:
- Added info text to the task editor which is shown in the recurrence tab if the due date is not set.
- The info text also notifies if the alarm won't be shown because it is either ignored in the calendar or the skin lacks the alarm window.
- Switching between events and tasks in the manager didn't update the menu items.
- Changing relative start or end time on an event or task which didn't define the property moved the time to start of year 0.
- Double click handler works in month view now too.
- Process completed functionality is disabled for Google tasks.
- Rainlendar_ReadFile() doesn't convert the text to lowercase anymore.
- The window specific settings dialog can be opened from the windows submenu.
- The snooze time can be relative to the target time (i.e. event's start or task's due time). Relative times can be defined with 'r' postfix (e.g. "10r").
- Added few predefined choices for the time and date formats in the advanced options.
- Updated the 3rd party libraries: curl, lua, openssl, zlib
- Created a workaround for a crash problem which happened on 64-bit Kubuntu when the event or todo dialog was closed.