Added specific routines for OUTPUT_DEBUG_STRING and EXCEPTION debug events.
Generate a breakpoint event on process attach.
Misc cleanups in request handling.

diff --git a/server/thread.c b/server/thread.c
index cf02b87..37db99b 100644
--- a/server/thread.c
+++ b/server/thread.c
@@ -126,6 +126,7 @@
     if (!(thread = alloc_object( &thread_ops, fd ))) return NULL;
 
     thread->unix_pid    = 0;  /* not known yet */
+    thread->context     = NULL;
     thread->teb         = NULL;
     thread->mutex       = NULL;
     thread->debug_ctx   = NULL;