fixed CTRL+C interruptions on Windows; optimized CTRL+C polling on Gtk+

* teco_interrupt() turned out to be unsuitable to kill child processes (eg. when <EB> hangs).
  Instead, we have Win32-specific code now.
* Since SIGINT can be ignored on UNIX, pressing CTRL+C was not guaranteed to kill the
  child process (eg. when <EB> hangs).
  At the same time, it makes sense to send SIGINT first, so programs can terminate gracefully.
  The behaviour has therefore been adapted: Interrupting with CTRL+C the first time will kill
  gracefully. The second time, a more agressive signal is sent to kill the child process.
  Unfortunately, this would be relatively tricky and complicated to do on Windows, so CTRL+C will always
  "hard-kill" the child process.
* Moreover, teco_interrupt() killed the entire process on Windows when called the second time.
  This resulted in any interruption to terminate SciTECO unexpectedly when tried the second time on Gtk/Win32.
* teco_sigint_occurred renamed to teco_interrupted:
  There may be several different sources for setting this flag.
* Checking for CTRL+C on Gtk involves driving the main event loop repeatedly.
  This is a very expensive operation. We now do that only every 100ms. This is still sufficient since
  keyboard input comes from humans.
  This optimization saves 75% runtime on Windows and 90% on Linux.
  * The same optimization turned out to be contraproductive on PDCurses/WinGUI.

0 files changed, 0 insertions, 0 deletions