the expression mm*j can in general not be represented as int, therefore
we need to convert each factor to double before multiplying them
handle limit case strike (including displacement) equals zero
fix maturities for tn and sn quotes,
avoid generating too many quotes (and reading undefined array elements),
write 15 and 35 for the number of FRAs and Swaps entering the curve
throughout the code
avoid unsigned int overflow runtime errors. Although the code probably
works on most (or all?) existing platforms without the changes, strictly
spoken there are undefined subexpressions which we eliminate here.
replace int with Integer
Merged pull request #31.

Some fixes for runtime errors occuring in the test suite
when running under clang's "-fsanitize=address,undefined,integer".