dlgWaypointDetails: Applied naming convention
dlgWaypointDetails: Merged duplicate code into loop
dlgWaypointDetails: Added UpdatePage() function

There is no need to call NextPage(0) if we only want to set
the visibilities.
dlgWaypointDetails: Calculate last_page value only once

This value is not changing so we don't need to calculate it every time the
buttons are pressed.
dlgWaypointDetails: Added UpdateZoomControls() function
dlgWaypointDetails: Removed parameters from UpdateCaption() function

There is only one caller and the parameters won't have any other values
than that anyway.
dlgWaypointDetails: Removed duplicate file_num check from UpdateCaption()
xcsoarswiftsplash.svg: Renamed to logo.svg
resource.h: Renamed IDB_SWIFT to IDB_LOGO
Math/fixed: fix ceil(), remove bit-wise NOT operator

The constexpr optimisation of ceil() caused severe breakage because
the operation was using a negated operand.
test/test_fixed: add tests for floor() and ceil()
Screen/Window: Added MoveToCenter() method
WidgetDialog: Added code comments
DigitEntry: Removed duplicate padding

The padding was already applied to the digit_size struct.
Dialogs/TimeEntry: Moved FixedWindowWidget to separate file
DataField/Enum: Use lambda function to sort entries
OrderedTask: simplify check in UpdateIdle()
TaskMinTarget: fix indent
Manual: First collection of files for a complete german manual translation.
Manual: Included german translation into "manual" and "dev-dist" build target.