From the release announcement:
The main changes in this version since the last release 2014-02-23 are:
* Added support for reading and writing boolean result formats.
* Fixed several query engine operator evaluations (AVG, STRBEFORE,
STRAFTER, CONCAT)
* Updated query results class constructor and methods, deprecating older.
* Portability fixes for ICC, clang and GCC 5.
* New internal test runner utility
* Variable bindings query results can be formatted in mKR CSV format.
* Multiple other fixes and improvements including fixing reported issues:
0000546, 0000568, 0000583 and 0000588.
For full details see the Rasqal 0.9.33 release notes at
http://librdf.org/rasqal/RELEASE.html#rel0_9_33