autotest: remove dependency on pexpect for rover/copter sim

this makes it easier to run on windows

Tools/autotest/pysim/util.py

@@ -1,6 +1,6 @@
 import math
 from math import sqrt, acos, cos, pi, sin, atan2
-import os, pexpect, sys, time, random
+import os, sys, time, random
 from rotmat import Vector3, Matrix3
 from subprocess import call, check_call,Popen, PIPE
 
@@ -110,6 +110,7 @@ def pexpect_close_all():
 
 def pexpect_drain(p):
     '''drain any pending input'''
+    import pexpect
     try:
         p.read_nonblocking(1000, timeout=0)
     except pexpect.TIMEOUT:
@@ -117,6 +118,7 @@ def pexpect_drain(p):
 
 def start_SIL(atype, valgrind=False, wipe=False, height=None):
     '''launch a SIL instance'''
+    import pexpect
     cmd=""
     if valgrind and os.path.exists('/usr/bin/valgrind'):
         cmd += 'valgrind -q --log-file=%s-valgrind.log ' % atype
@@ -134,6 +136,7 @@ def start_SIL(atype, valgrind=False, wipe=False, height=None):
 def start_MAVProxy_SIL(atype, aircraft=None, setup=False, master='tcp:127.0.0.1:5760',
                        options=None, logfile=sys.stdout):
     '''launch mavproxy connected to a SIL instance'''
+    import pexpect
     global close_list
     MAVPROXY = os.getenv('MAVPROXY_CMD', reltopdir('../MAVProxy/mavproxy.py'))
     cmd = MAVPROXY + ' --master=%s --out=127.0.0.1:14550' % master
@@ -153,6 +156,7 @@ def start_MAVProxy_SIL(atype, aircraft=None, setup=False, master='tcp:127.0.0.1:
 def expect_setup_callback(e, callback):
     '''setup a callback that is called once a second while waiting for
        patterns'''
+    import pexpect
     def _expect_callback(pattern, timeout=e.timeout):
         tstart = time.time()
         while time.time() < tstart + timeout: