add adiff, thukral, multroot
update readme, fix ctr error
minor changes
tidy
add thukral16 method
add 5th order derivative free method
adjust algorithm
error in approx deriv
tweaks to update methods
update readme
add Base. prefix
return xn1, not xn
work on convergence issues
Merge pull request #4 from jverzani/jv

Merge in fzero interface, multroot and thukral algorithm