[Calendar] Exchange the "current day" button with the "new event" button

[themeles]

Opening the calendar app already takes the user to the current date. There are also a couple of other methodes (like Today scope) to display, whats going on today.

When checked whats going on today, the next thing might be to go to a specific date and create an event there. This will happen more often than going back to the current date, so the position of this button should be prioritized.

For this reason I would suggest to move the "new event" button to the toolbar, and the "current day" button to the menu.

This bug is related to bug 1479277, since in the month view the only possible option to create an event is via the button in the menu.

UX Comment:

I completely agree that the presence of the active 'current day' item in the header is somewhat miss-leading when a user is already viewing their current day as it will do nothing when pressed.

However, 'New Event' was not designed to appear in the header (or as you called it "menu"). The design has always proposed that 'New Event' is the primary action for the app, and as such should be accessed via a bottom-edge swipe (as shown in the spec - https://docs.google.com/presentation/d/14NIPecPFKb_8Ad3O4suEGJqVOw9bC4n0s63uWalbZ98/edit#slide=id.g4160a5a3b_021).

Alternatively, the user may long-press within a specific time slot for a given day to quickly create a new event on that day (meaning that if we also have 'New event' as an item in the header there are 3 methods of creating new events in total - somewhat redundant!).

I would propose that rather than repeating functionality that is already present within the U.I, the 'current day' item in the header area should be shown as disabled (greyed out) when the current day is already being viewed.
That way we avoid introducing inconsistency in the U.I (with header items appearing and disappearing) while also avoiding introducing a third method for creating new events.