Revision 2642

First step towards unicode.  With this roughly we're at step 1
string_representation.txt

* Doc/technotes/string_representation.txt: New.  Document how
strings are represented in Thuban and how to get to a Unicode
Thuban.

* Thuban/__init__.py (set_internal_encoding)
(unicode_from_internal, internal_from_unicode): New. The first few
functions for the internal string representation

* Thuban/UI/about.py (unicodeToLocale): Removed.  Use
internal_from_unicode instead.

* Thuban/UI/__init__.py (install_wx_translation): Determine the
encoding to use for the internal string representation.  Also,
change the translation function to return strings in internal
representation even on unicode builds of wxPython

* Thuban/Model/load.py (SessionLoader.check_attrs): Decode
filenames too.
(SessionLoader.start_clrange): Use check_attrs to decode and check
the attributes.

* Thuban/Model/xmlreader.py (XMLReader.encode): Use
internal_from_unicode to convert unicode strings.

* Thuban/Model/xmlwriter.py (XMLWriter.encode): Use
unicode_from_internal when applicable

* test/runtests.py (main): New command line option:
internal-encoding to specify the internal string encoding to use
in the tests.

* test/support.py (initthuban): Set the internal encoding to
latin-1

* test/test_load.py (TestSingleLayer.test, TestClassification.test)
(TestLabelLayer.test): Use the internal string representation when
dealing with non-ascii characters

* test/test_load_1_0.py (TestSingleLayer.test)
(TestClassification.test, TestLabelLayer.test): Use the internal
string representation when dealing with non-ascii characters

* test/test_load_0_9.py (TestSingleLayer.test)
(TestClassification.test): Use the internal string representation
when dealing with non-ascii characters

* test/test_load_0_8.py (TestUnicodeStrings.test): Use the
internal string representation when dealing with non-ascii
characters

* test/test_save.py (XMLWriterTest.testEncode)
(SaveSessionTest.testClassifiedLayer): Use the internal string
representation when dealing with non-ascii characters where
applicable