(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/BTU.t

@@ -0,0 +1,74 @@
+.TH Concept "Bureaucratic Time Units"
+.NA BTU "How BTUs are generated"
+.LV Expert
+.s1
+It takes time for decisions to be made by top level officials, and it
+takes time for their orders to reach those who execute them.
+The potential of your government to process new information is
+measured in Bureaucratic Time Units (BTU).
+.s1
+BTUs are generated in real-time based on the number of civilians that
+are in your capital.  Every time you log out and in again, the server
+calculates how long you've been away, and based on that time awards
+you a certain number of BTUs.
+.s1
+Here is the procedure for determining how many BTUs you get:
+.nf
+If the game is a blitz, then as soon as your BTUs go below zero, then
+they are automatically set back to 512.
+
+(1) Count the number of civs generating BTUs.
+  civs = maximum(999, number of civs in your capital sector)
+  Note that if you don't have a capital, then you will get _no_ BTUs.
+
+(2) Find out how many civs are required to make one BTU in one time unit.
+The "version" command will tell you how many civilians are required to
+produce one BTU in one time unit.
+
+(3) Calculate how many BTUs your cap produces in one time unit.
+Divide the number of civs generating BTUs (step 1) by the number of
+civs required to produce one BTU in one time unit (step 2).  If your
+capital is in a mountain or has zero efficiency, then multiply by
+1/200.  Otherwise, multiply by (sector efficiency) / 100.  Note that
+0% capitals and mountains generate BTUs as if they were 0.5% capitals.
+
+(4) Calculate how many time units have passed.
+The number of "Time units" (TU) since your last login is:
+  TU = (number of seconds since last login) / (number of seconds per ETU).
+The "version" command will tell you how many seconds are in an
+"Empire time unit" (ETU).  If more than 336 time units have passed
+since your last login, then set TU = 336.
+
+(5) Calculate how many BTUs you get.
+Multiply the number of BTUs your cap produces in one TU (step 3) by
+the number of TUs which have passed (step 4).  This is how many BTUs
+you get.  Note that there is a limit to how many BTUs you can have at
+any given time.  This number is usually 512 but can be changed by the deity.
+
+EXAMPLE: say you had a 100% capital containing 500 civs.
+Suppose that version said:
+
+It takes 25.00 civilians to produce a BTU in one time unit
+
+Then first you would divide 500 by 25 to get 20.  Now since your cap
+is 100% efficient, you would multiply 20 by (100/100) and so the civs
+in your cap would produce 20 BTUs per time unit.  Now suppose that
+version said:
+
+An Empire time unit is 1440 seconds long.
+
+and suppose that 1 day had passed since the last time you logged on.
+Then that means that the number of time units which have passed is:
+  TU = (number of second in a day) / (number of seconds per etu)
+     = (24 * 60 * 60) / (1440)
+     = (1440 * 60) / (1440)
+     = 60
+(Note that another way to find out how many time units there are between
+updates is to find out how many ETU's there are per update.)
+  Lastly, we multiply 20 by 60 to get 1200 BTUs.  But since the
+maximum is 512, we would have 512 BTUs.  Note that if your capital had
+been in a mountain sector, then you would have only gotten 6 BTUs in
+24 hours.
+.fi
+.s1
+.SA "Innards, version, Time, Playing"