ware_besch.h:  Enter comments related to speed bonus calculation, in prep for revenue rework
Relocate calc_adjusted_speedbonus to ware_besch_t::get_adjusted_speedbonus.  Rewrite to eliminate several bugs in it.  Prepare for unit change.
Merge branch 'ncn-devel' into mail-revenue
Merge branch 'ncn-devel' into mail-revenue
Merge branch 'ncn-devel' into mail-revenue
CODE: Remove vestiges of "COMMAND_LINE_SERVER": COLOUR_DEPTH=0 works automatically now.
FIX: Possible integer overflow in calculating delta_t
FIX: Revert correct colour for the progress bar
Merge branch 'ncn-devel' into mail-revenue
Merge branch 'ncn-devel' of git://github.com/neroden/simutrans.git into 112.x-private-car-merge
CODE: Removed the "mno-cygwin" reference in the Makefile.
FIX: Possible fix to end of month/dingelist related crashes.
Add speed/time/distance conversion routines to simunits.h
Small comment improvement
Add passengers discarded due to waiting too long to the "too slow" graph, not the "unhappy" graph (which represents overcrowding)
Make get_unhappy_percentage readable.
Relocate main revenue calculation and speedbonus code to ware_besch_t.  Eliminate multiple bugs in goods frame by using same subroutine for it and revenue.  Reorganize early revenue code in simconvoi.cc.  Reorganize speed bonus handling and fix treatment of wtype and welt variables in gui/goods_frame_t and gui/goods_stats_t.  Fix bad uses of "const" in simconvoi.
Merge branch 'ncn-devel' into mail-revenue
Add "dumb" logging implementation to allow for writing unit tests.
Add piecewise_linear_tpl to abstract out the various piecewise-linear computations already present in experimental.
Revert "Add passengers discarded due to waiting too long to the "too slow" graph, not the "unhappy" graph (which represents overcrowding)"

This reverts commit ef4871750d5ae889a51756e9f2102338f8ad3695.