Update the news file for 0.4.a2
Update prompt selection script

* Make a separate script which selects "nice" sentences from Wikipedia
* Support both bigrams and diphones
Restructure the initial tokenazation and sentence splitting code
document::create_from_plain_text: change the type of the forth
argument
Fix a typo
Add support for speaking key names
English: in contractions interpret U+2019 as an apostrophe
Limit maximum length of sentences and tokens
Fix a typo
Ini parser: optionally process a file without converting lines to
key/value pairs
An implementation of a patricia trie for storing user dictionaries
A separate class for storing and applying stress information
Add a method to the implementation of a trie to try lowercase
alternatives if the exact search fails
Fix a programming error, because of which we referenced destroyed objects
Fix a bug in the implementation of a patricia trie
Implement a user pronunciation dictionary

The format is not compatible with the older versions of RHVoice. We do
not rely on regular expressions any more. Instead we use the lemon
parser generator to create a parser for this new format.