Render bomber routes during the raid (post-GEE only)
Render the seltarg route in the control screen
Allow to change the route for post-GEE raids
Give an indication of (rough) payloads for the selected route
Hide the payload estimations on LEAFLET targets

Leaflet payloads are always bombertype.cap*3, regardless of flight distance.
Smoothly spread the weather over 24 hours
Fix and rationalise run_raid time conversions & absolute time constants
Make zero hour a parameter.  No UI to set it yet.

Note that this necessitated the removal of the plan/act/skym/fires graph
 as there is no longer a single hour in which all raids should happen.
It might be possible to resuscitate the graph with "time - zerohour" as
 the x-axis, but this would be (a) rather complicated to implement and
 (b) rather confusing for the user.
Add UI to control Zero Hour for routeable (i.e. post-GEE) raids
Fix control's quit handler to call clear_raids

Previously had open-coded (and outdated) version.
Document manual routing and Zero Hour control in HOWTOPLAY
Change NoType save-format to be more regular

The old format lacked a colon, which confused stats/hsave.py
If bomber fails after bombing, stay with the bomber stream

Previously, any bomber with .failed=true set course immediately for
 base.  Now this only happens if they haven't bombed yet (they
 jettison their bombload and turn for home); otherwise, they stick
 to the planned route as this gives them the protection of the
 bomber stream.
stats: only show bombertypes that actually exist in the graphs

That is, only those types for which at least one bomber of that type was
 in service during the period being graphed.
Also, profit.py and losstype.py omit nonexistent bomber types, but only
 if they were deselected (ie. NoType: in the save file).
Fix route-following code to not be confused by reversed course

Previously, a westbound leg on the outward flight or an eastbound leg on the
 return flight would be skipped, because a turning-point was considered
 'reached' as soon as its longitude was passed.  Now we instead work in a
 co-ordinate system such that the current leg of the route is the 'x'
 direction - i.e. on a route leg AB, if we are at C, the leg is finished if
 angle ABC exceeds 90°.  This is easily computed as (AB)·(CB) < 0.
stats: fix bug in hsave parsing of bools (bomber.fail, bomber.pff)

bool('0') is True, which is not what we wanted.
stats: add new totalraids & totalraidgraph