minimizing RAM use

[yakra]

• In class headers, pay attention to alignment requirements. Order data elements to minimize wasted space and sizeof. Pointers first?
• Consider using bitmasks for multiple bools. Why waste 7+ bits?
  • HGEdge::s/c/t_written (Done, and later replaced with TMBitsets in d218c4d)
• Try unions.
• vectors instead of lists where possible -- eliminate pointers to prev/next item.
• vectors instead of deques.
  • Waypoint::alt_labels (7874c4c)
  • Route::alt_route_names (616425b)
• std::vector::reserve before populating #190
• std::vector::shrink_to_fit()
• std::string::shrink_to_fit()
• Replace Waypoint::is_hidden with a function (except that there's 4B dead space after point_num anyway).
• list_entry_name & route_names_and_systems #175

[yakra]

as of 383f269:

class	sizeof	alignof
Args	1	1
ClinchedDBValues	192	8
ConnectedRoute	136	8
Datacheck	176	8
ElapsedTime	48	8
DBFieldLength	1	1
ErrorList	64	8
GraphListEntry	104	8
HGEdge	136	8
HGVertex	128	8
HighwaySegment	144	8
HighwaySystem	472	8
HighwayGraph	24664	8
PlaceRadius	88	8
Region	240	8
Route	728	8
TravelerList	352	8
Waypoint	192	8
WaypointQuadtree	152	8