Basic Text Extraction
---------------------

For basic text extraction, make use of 
org.apache.poi.extractor.PowerPointExtractor. It accepts a file or an input
stream. The getText() method can be used to get the text from the slides,
from the notes, or from both.


Specific Text Extraction
------------------------

To get specific bits of text, first create a org.apache.poi.usermodel.SlideShow
(from a org.apache.poi.HSLFSlideShow, which accepts a file or an input
stream). Use getSlides() and getNotes() to get the slides and notes.
These can be queried to get their page ID (though they should be returned
in the right order). You can also call getTextRuns() on these, to get their
blocks of text. From the TextRun, you can extract the text, and check
what type of text it is (eg Body, Title)


Changing Text
-------------

It is possible to change the text via TextRun.setText(String). However, if
the length of the text is changed, things will break because PowerPoint has
internal file references in byte offsets, which are not yet all updated when
the size changes.


Guide to key classes
--------------------

org.apache.poi.hslf.HSLFSlideShow
  Handles reading in and writing out files. Generates a tree of the records
  in the file
org.apache.poi.hslf.usermode.SlideShow
  Builds up model entries from the records, and presents a user facing
  view of the file
org.apache.poi.hslf.extractor.PowerPointExtractor
  Uses the model code to allow extraction of text from files