More #!/usr/bin/env python

There are some more examples of things which might break:
```
$ grep -r '/usr/bin/'|grep '/usr/bin/env' -v
Makefile:       if [ -f /usr/bin/yum ] ; then yum install gmp strace python-argparse python-ply python-gevent; else apt-get install libgmp10 strace python-ply python-gevent; fi
cpp/runpython.cpp:    statok = stat("/usr/bin/python", &statbuf);
debian/connectal.install:/usr/bin/pcieflat
debian/rules:#!/usr/bin/make -f
examples/gyro_simple/test_gyro.py:            octave_file.write("#! /usr/bin/octave --persist \nv = [");
scripts/Doxyfile:PERL_PATH              = /usr/bin/perl
tests/spikehw/README.md:    Running /usr/bin/pciescan.sh
```
Of these, the three I think would break are the `runpython.cpp`,
`Doxyfile` and the `test_gyro.py`.
- The runpython.cpp possibly needs to be patched up to search along
  $PATH, which is a more substantial change so I have left it as is for
  now.
- The Doxyfile says it requires an absolute path.
- I can't just do `#! /usr/bin/env octave ...` because env doesn't do
  arguments, so I have left it as is.

examples/echopy/testecho.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # Copyright (c) 2014 Quanta Research Cambridge, Inc
 #
 # Permission is hereby granted, free of charge, to any person obtaining a

generated/scripts/importbvi.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # Copyright (c) 2013 Quanta Research Cambridge, Inc.
 #
 # Permission is hereby granted, free of charge, to any person

jtag/dumptrace.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # Copyright (c) 2013 Quanta Research Cambridge, Inc.
 #
 # Permission is hereby granted, free of charge, to any person

jtag/readll.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # Copyright (c) 2013 Quanta Research Cambridge, Inc.
 #
 # Permission is hereby granted, free of charge, to any person

pcie/pcieflat

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # Copyright (c) 2014 Quanta Research Cambridge, Inc
 #
 # Permission is hereby granted, free of charge, to any person obtaining a

pcie/tlp.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 
 import os
 import re

scripts/boardinfo.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # Copyright (c) 2014 Quanta Research Cambridge, Inc.
 #
 # Permission is hereby granted, free of charge, to any person

scripts/bsv.filter

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # Usage doxyfilter_bsv.psv < infile.bsv > outfile.java
 
 import fileinput

scripts/bsvdepend.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # Copyright (c) 2015 Connectal Project
 #
 # Permission is hereby granted, free of charge, to any person obtaining a

scripts/bsvdependencies.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # Copyright (c) 2015 Connectal Project
 #
 # Permission is hereby granted, free of charge, to any person obtaining a

scripts/bsvpreprocess.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # Copyright (c) 2014-2015 Quanta Research Cambridge, Inc
 # Copyright (c) 2015 Connectal Project
 #

scripts/check-timing.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 
 import sys, re
 

scripts/extract-bvi-schedule.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # Copyright (c) 2015 Connectal Project
 #
 # Permission is hereby granted, free of charge, to any person obtaining a

scripts/generate-constraints.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # Copyright (c) 2013 Quanta Research Cambridge, Inc.
 #
 # Permission is hereby granted, free of charge, to any person

scripts/globalv.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 
 globaldecls = []
 globalvars = {}

scripts/makefilegen.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 ## Copyright (c) 2013-2014 Quanta Research Cambridge, Inc.
 
 ## Permission is hereby granted, free of charge, to any person

scripts/packagesource.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 
 import os, sys
 import glob

scripts/parse_qsf.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 
 from __future__ import print_function
 import sys

scripts/parse_xdc.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 
 # parse xdc pin assignment to json
 

scripts/portal.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # Copyright (c) 2016 Connectal Project
 #
 # Permission is hereby granted, free of charge, to any person obtaining a

scripts/reorderbytes.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # Copyright (c) 2014 Quanta Research Cambridge, Inc.
 #
 # Permission is hereby granted, free of charge, to any person

scripts/syntax.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # Copyright (c) 2014 Quanta Research Cambridge, Inc
 #
 # Permission is hereby granted, free of charge, to any person obtaining a

tests/bluecheck_harness/harness.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # Copyright (c) 2016 Connectal Project
 #
 # Permission is hereby granted, free of charge, to any person obtaining a