(info, html): Implement.

(all): Depend on info.

Flatten info directory.  This undoes the move to one subdirectory per
chapter, which was done during Empire 2.  The structure doesn't buy us
much, as the info name space is flat, and it complicates makefiles.

Overhaul info.pl:
- It now wants to run in the root of the build tree.
- Information on source files and subjects is now stored in makefiles,
  thus info.pl no longer picks up random junk from the file system.
- Clean up Perl anachronisms, in particular use subroutine arguments and
  results rather than global variables where convenient.
- Change format of diagnostics to the common format used by GNU tools,
  so that Emacs and the like can parse it.
- Catch missing .SA.
- When creating a new subject file, cowardly refuse to overwrite an
  existing file.
- Subject files contain topics sorted by chapter, then by name.  The
  order of chapters used to depend on how Perl sorts hash keys.  Fix
  it.

info/level.t

@@ -0,0 +1,75 @@
+.TH Command LEVEL
+.NA level "List distribution thresholds"
+.LV Basic
+.SY "level <SECTS>"
+The level report provides information about the various 
+distribution thresholds in some or all of the sectors that
+you occupy.
+.s1
+In the syntax of the level command
+<SECTS> is the area on which you wish information,
+(see \*Qinfo syntax\*U).
+A typical usage might be:
+.EX level -6:6,-3:3
+which would list data for the area extending three sectors
+out from the capital in each direction.
+.s1
+The level report lists each of your sectors with the following heading:
+.NF
+DISTRIBUTION LEVELS
+ sect    dst   civ mil uw food  sh gun pet iron dust bar oil lcm hcm rad
+.FI
+These columns represent:
+.s1
+.in \w'path------\0\0'u
+.L sect
+the x and y coordinates of the sector
+.L path------
+the route that goods travel to and from the distribution sector
+.L dst
+the distribution destination for the sector
+.L civ
+the distribution threshold for civilians in that sector
+.L mil
+the distribution threshold for military in that sector
+.L uw
+the distribution threshold for uncompensated workers in that sector
+.L food
+the distribution threshold for food in that sector
+.L gun
+the distribution threshold for guns in that sector
+.L sh
+the distribution threshold for shells in that sector
+.L pet
+the distribution threshold for petroleum in that sector
+.L iron
+the distribution threshold for iron ore in that sector
+.L dust
+the distribution threshold for gold dust in that sector
+.L bar
+the distribution threshold for gold bars in that sector
+.L oil
+the distribution threshold for oil in that sector
+.L lcm
+the distribution threshold for light construction materials
+in that sector
+.L hcm
+the distribution threshold for heavy construction materials
+in that sector
+.L rad
+the distribution threshold for radioactive materials in that sector
+.in
+.s1
+For example:
+.EX level -2,2
+.NF
+.ps -1
+Fri Oct 31 16:58:34 1986
+DISTRIBUTION LEVELS
+ sect    dst   civ mil  uw food  sh gun pet iron dust bar oil lcm hcm rad
+-2,-2 + -2,-2    0   0 201    0   0   0   0    0    0   0   0   0   0   0
+   1 sector
+.ps +1
+.FI
+.s1
+.SA "distribute, threshold, commodity, census, Distribution"