(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/capital.t

@@ -0,0 +1,48 @@
+.TH Command CAPITAL
+.NA capital "Change the location of your capital"
+.LV Basic
+.SY "capital <SECTOR>"
+This command changes the location of your nation's capital.
+The new sector must be of type "capital" or "mountain",
+and must be owned by you.  Your capital produces BTUs.  See "info BTU"
+for the exact rate of BTU production.
+.s1
+This command does not change your coordinate origin
+(where 0,0 is located),
+so if you prefer your coordinates centered on your nation's capital,
+you must use the origin command.
+For example:
+.EX capit -10,-4
+.NF
+Your capital is now at -10,-4.
+.FI
+.EX orig -10,-4
+.NF
+Designation of new origin requires revision of sector numbers.
+Origin at -10,-4 (old system) is now at 0,0 (new system).
+.FI
+.s1
+If the unthinkable should come to pass, and an enemy captures your capital,
+bad things happen. Some happen once, immediately:
+
+.NF
+1) You will lose half your cash, or $3K, whichever is more.
+2) Your enemy will gain half your cash times (1/5 + 4/5 * sector efficiency)
+.FI
+.s1
+Re-taking a previously taken capital has no further effect. Once a new capital
+has been declared with this command,
+you are again in peril of these two awful things.
+.s1
+Some effects happen right away, and last until you use
+the \*Qcapital\*U command to create a new capital. The effects are:
+
+.NF
+3) You will not be able to use many commands (use the 
+   'list of commands' command to see the pitiful few you may still use)
+
+4) The rate at which you gain BTUs will dramatically decrease (see
+   info BTU).
+.FI
+.s1
+.SA "origin, designate, BTU, Nations"