TODO
====

o Add support for multiple accounts;
o Implement correct method for checking new messages with
  IMAP (don't use RECENT command, but NEW command);
o Implement the volume for the console beep;
o Test if the 'execcommand' variable in the configuration file points to
  a valid executable (double-click action);
o In configure.in, is the check to "sys/types" necessary?
o In pop3.c, gethostbyname() blocks for a long time if network is unavailable;
  Try alternative to this blocking mode (timeout value?);
o The volume setting in the configuration file is in percentage, but it is not computed
  as a logarithmic function in file sound.c (dB);