Bugfix in binary unpacking
libhyphen-native for Mac OS
braillecss: add 'string-set' to supported-css.xsl
liblouis-formatter: enable pre-hyphenation mode
xml-to-pef: simplify design:

* remove concept of a 'preprocessor', everything is a 'translator' now
* a translator is now by default a document-level translator (former preprocessor)
* a block-level translator can be created by extending block-translator-template.xsl
* the block-extraction and -processing is now all done in XSLT instead of XProc (p:viewport + cx:eval), which results in a significant increase in speed
* also, Calabash issue #82 (Problems with cx:eval) is not so critical anymore