changed: types used in the ParserManager are
defined in bigtypes.h
changed: a new class Convert
all variables and methods regarding
converting are thrown into Convert class
changed: Convert uses two values during converting
(numerator and denominator)
git-svn-id: svn://ttmath.org/publicrep/ttcalc/trunk@77 e52654a7-88a9-db11-a3e9-0013d4bc506e
