RAIN high-level API

Simple interface for RAIN users (programmers):

For C/C++ in real/protected mode use rain.h.
For Pascal in real/protected mode use unit rain.pas.

  After program startup, communication protocol is set to no communication.
  Everything works, but in silence.
  RainInit reads environment string RAIN= and selects better communication
  protocol if possible. Further RainInit calls are ignored.
  Returns RAIN version string, empty for no communication.
  Note: There is no destructor. You don't even have to stop playing sounds
  when you finish.

  Call it time from time.
  If you don't, reports might lay unnoticed until next rain call (any call)
  and sound output may be interrupted until next RainPoll() call.

  Starts playing sound located in file filename at offset fileofs and
  filesize bytes long. When fileofs=filesize=0, whole file is taken.
  File type is detected from its contents.
  Currently supported file types: mod,s3m,xm,(it),(iff),wav,mp3.
  When loop=0, sound is played just once and end is reported to Reporter.
  When loop<>0, sound is repeated until you stop it with RainStop().
  Always returns runtime-unique non-zero sound handle even if
  sound may not be played. In this case report that sound is over follows.

  Sets sound volume. Range 0..64.
  Note: You may call any function with invalid handle and nothing will happen.

  Sets sound panning. Range -64..64.
  Has no effect on modules.

  Stops sound.
  End is not reported to Reporter.

  Sets volume amplification. 100 is default, 200 is twice louder etc.
  New value overrides previous one.

  Reporters are callback functions - variables of procedure(report) type.
  They are called from Rain commands with error and other reports.
  You may issue other Rain commands from reporter, but in this case
  it must be reentrant, because commands may call reporters.
  You may change reporters at any time.

  Error messages are reported to ReportError(string).
  Default ReportError echoes messages to stderr.

  Ends of non-looping sounds are reported to ReportEnd(handle).
  Default ReportEnd does nothing.

  Only in case you call Rain command asynchronously, for example you hook
  RainPoll to timer:
  Increase async before every asynchronous call and decrease it after.
  Rain won't report any errors until next synchronous call.
  It's just for your pleasure, you won't have to think what may happen
  and how to solve it when your Reporter is called asynchronously.
  Note: Asynchronous call may be ignored if it's not possible to execute it
  immediately (DOS safety flag not set or synchronous Rain command processed).
  Note: Sound ends are always reported immediately. If you call RAIN
  asynchronously, ReportEnd must be safe (prepared for asynchronous call).