Added two keyword arguments to Template.__init__(): "default_encoding" and
"decode_errors".  These are passed internally to unicode() as the "encoding"
and "errors" arguments when converting strings of type str to unicode.

From the issue:

    The constructor `Template.__init__()` should accept an optional
    `escape` function argument instead of the boolean `disable_escape`.
    This is more natural.

    Examples:

     * Users wanting to disable escaping can pass `lambda s: s`.
     * Non-markupsafe users wanting double-quotes escaped can pass
       `lambda s: cgi.escape(s, True)`.  The cgi.escape() function
       doesn't escape double-quotes by default.
     * Similarly, markupsafe users can specify an alternative to
       `markupsafe.escape()`.

Added a passing test case to cover issue #53.

From: https://github.com/cjerdonek/pystache/commit/7e130676d3523db4e936e5f8f726c1493b2cbd31
Into: issue_53

Adds a test case to cover issue #53.

Conflicts:
	tests/test_pystache.py

Markupsafe can now be turned on and off (for testing purposes).
The unit tests now run test_pystache.py twice if markupsafe is
enabled: once with and once without.  Moreover, all unit tests
now pass.  Previously, one test case in test_pystache.py failed
with markupsafe enabled.

The above change was initially made for testing purpose.  The unit
tests now run the test cases in test_pystache.py twice if markupsafe
is available: once with markupsafe enabled and once without.  All
unit tests now pass using markupsafe (there was previously one
failing test in test_pystache.py: test_non_strings).

Added a unit test to show that the issue is no longer present:
section list items do have access to the parent context.