* Writing support added to the SummaryInformation and DocumentSummaryInformation...

* Writing support added to the SummaryInformation and DocumentSummaryInformation classes. These classes now have methods for setting and removing properties. Coherent extensions are:
** Documentation section about writing standard properties added to the HPSF HOW-TO.
** Example application added showing how to modify the document summary information.
** Testcases added for testing modifying summary information and document summary information.
** PropertySetFactory extended to create SummaryInformation and DocumentSummaryInformation instances.

* Added MutablePropertySet.write(DirectoryEntry, String) to ease writing a property set to a POI filesystem document.

* Improved codepage handling.

* Bug fixed: Integral values were read and written as unsigned instead of signed.

* Reworked the mapping between variant types and Java types: Variant.VT_I4 is mapped to Integer now and Variant.VT_I8 to Long. This might cause incompatibilities if you are doing low-level HPSF programming.

* Changed SectionIDMap.DOCUMENT_SUMMARY_INFORMATION_ID from a byte[] to a byte[][] in order to contain the format ID of the first and the second section. This is an incompatible change!

* Added PropertySet.getFirstSection(). This method is similar to getSingleSection() won't choke if the property set has more than one section.

* Support for low-level reading and writing of Variant.VT_I8 type properties added.

* Unnecessary casts removed.

* Poibrowser's display format changed slightly.

git-svn-id: https://svn.apache.org/repos/asf/jakarta/poi/trunk@382887 13f79535-47bb-0310-9956-ffa450edef68