added encoding support to dictionary import functions

added readLIWCdict() to read LIWC-formatted dictionaries

fixed a "bug"/feature in readWStatDict() that eliminated wildcards (and all other punctuation marks) - now only converts to lower.
updated pdf manual
working on supervised learning code
testing properties of regression methods
updated DESCRIPTION to fix data.table dependency.
Moved vignette to NEEDS FIXING as we will move all of these into the docbook in any case.
Improved clean().
Added compoundWords() to turn phrases into tokens.
Added thesaurus function to dfm().
added keep argument to dfm(), incremented version.
Added keep argument to dfmtrim().
Added nfeature.dfm().
Simplified clean().
updated pdf and Readme
remove whitespace from dictionary values
merging