Fix upper/lower bound calculation in model constraint.

Backported from master.
Fixed a Schedule bug.

A combination of backwards generation and end-of-month convention
could result in missing or duplicated first dates.

Thanks to Nicholas Manganaro for the heads-up.
Update ChangeLog.
add upper and lower bound to projected constraint
Fix a few Doxygen comments.
Bump version number to 1.4.1.
Merge remote-tracking branch 'official/R01040x-branch' into R01040x-branch

Conflicts:
	QuantLib-SWIG/Guile/setup.scm
	QuantLib-SWIG/MzScheme/setup.scm
	QuantLib-SWIG/Perl/Makefile.PL
	QuantLib-SWIG/Python/setup.py
	QuantLib-SWIG/Ruby/setup.rb
	QuantLib-SWIG/SWIG/ql.i
	QuantLib-SWIG/configure.ac
	QuantLib/Announce.txt
	QuantLib/configure.ac
	QuantLib/ql/version.hpp
	dev_tools/version_number.txt