Write a bunch of module documentation.

This commit adds or improves the module-level documenation for:

  buffers.c circuitstats.c command.c connection_edge.c control.c
  cpuworker.c crypto_curve25519.c crypto_curve25519.h
  crypto_ed25519.c crypto_format.c dircollate.c dirserv.c dns.c
  dns_structs.h fp_pair.c geoip.c hibernate.c keypin.c ntmain.c
  onion.c onion_fast.c onion_ntor.c onion_tap.c periodic.c
  protover.c protover.h reasons.c rephist.c replaycache.c
  routerlist.c routerparse.c routerset.c statefile.c status.c
  tor_main.c workqueue.c

In particular, I've tried to explain (for each documented module)
what each module does, what's in it, what the big idea is, why it
belongs in Tor, and who calls it.  In a few cases, I've added TODO
notes about refactoring opportunities.

I've also renamed an argument, and fixed a few DOCDOC comments.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/or/tor_main.c b/src/or/tor_main.c
index 21fbe3efb5..d67eda2ac9 100644
--- a/src/or/tor_main.c
+++ b/src/or/tor_main.c
@@ -17,8 +17,10 @@ const char tor_git_revision[] =
 
 /**
  * \file tor_main.c
- * \brief Stub module containing a main() function. Allows unit
- * test binary to link against main.c.
+ * \brief Stub module containing a main() function.
+ *
+ * We keep the main function in a separate module so that the unit
+ * tests, which have their own main()s, can link against main.c.
  **/
 
 int tor_main(int argc, char *argv[]);