Rewrite get_open_files

[mrjefftang]

I rewrote get_open_files to clean up a lot of the code and to address the error cases where handles or memory aren't closed/free'd.

This will address #542 since the access mask check is removed.

Hopefully this will address the newest issue in #340 but I don't have a Windows machine with bluetooth to test that. Maybe @jimbo1969 can retest this.

[mrjefftang]

I closed/re-opened the PR to trigger a new build and it looks like that test case that initially failed is nondeterministic.

[giampaolo]

Have you tested this on both Python 2 and 3? Do "make.bat test" and "make.bat test-memleaks" pass?

[mrjefftang]

Note that I still think the way forward is to go the Sysinternals Handles route and spawn a thread that calls NtQueryObject and waits a for a timeout and kills it off. Looks like we can avoid the associated memory leaks by converting the thread to a fiber.

Fixed an issue that looks like it was in the master branch relating to Process.ppid() on Windows.

Test failure on Python 3.4 is related to memory leak for net_if_addrs:

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FAIL: test_net_if_addrs (__main__.TestModuleFunctionsLeaks)
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Traceback (most recent call last):
  File "test\test_memory_leaks.py", line 413, in test_net_if_addrs
    self.execute('net_if_addrs')
  File "test\test_memory_leaks.py", line 86, in execute
    % (rss2, rss3, difference))
AssertionError: rss2=17768448, rss3=18120704, difference=352256
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Python 2.7:

======================================================================
FAIL: test_net_if_stats (__main__.TestModuleFunctionsLeaks)
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Traceback (most recent call last):
  File "test\test_memory_leaks.py", line 417, in test_net_if_stats
    self.execute('net_if_stats')
  File "test\test_memory_leaks.py", line 86, in execute
    % (rss2, rss3, difference))
AssertionError: rss2=12668928, rss3=13201408, difference=532480

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