Xlutils

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- add extremely limited formatting_info support to DummyBook and TestReader

- move to testfixtures 1.5.3 for tests

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- add and implement `start` method to components in xlutils.filter.

- fixed bug when using set_rdsheet with ColumnTrimmer.

- improved installation documentation.

- renamed xlutils.styles.CellStyle to more appropriate
xlutils.styles.NamedStyle.

- improved documentation for xlutils.styles.

- moved to using TestFixtures and Mock for tests.

- moved to using ErrorHandler rather than duplicating code.

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- prevented generation of excessively long sheet names that cause
Excel to complain.

- added test that will fail if the filesystem used doesn't support
filenames with +'s in them.

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- link to the documentation for xlutils.display

- tighten up version requirements for xlrd and xlwt

- use style compression in xlutils.filter.BaseWriter

- prevent generation of bogus sheet names in xlutils.filter.BaseWriter

- xlutils.filter.BaseFilter now keeps track of rdbook, simplifying the
implementation of filters.

- add another example for xlutils.filter

- add xlutils.filter.XLRDReader

- add xlutils.filter.StreamWriter

- add xlutils.styles

- add xlutils.save

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- initial public release