new impl for erfinv/erfcinv with tests added
remains to change one polynomial evaluation as soon as the maximal degree for horner use will be increased
merging master
improving erf(c)inv and adding tests
 correcting some doxy in euler
correcting some misprints indicated by mathias
suppressing a trailing comment
some blanks not needed
merge master in improving_erfinv
using new horner in erfinv
correcting expni include and bad test in erfcinv unit
Merge pull request #719 from jtlap/improving_erfinv

Improving erfinv