fix-B[f]

I think this is a better fix than the hack in SIE, but still not
completely satisfied. Allows addentries! and domain and range spaces
for H[w].
Updates to Sigma

Sigma has a domain and range space.
Addentries! is updated for all ultraspherical spaces since they’re
orthogonal with the weight (1-x^2)^{\lambda-1/2}.
Included Sigma tests.
Nonnegative ultraspherical spaces
typo in tests
LowRankFun and Fun algebra
Correct parameterization
Merge pull request #75 from ApproxFun/feature-update-Sigma

Feature update sigma
Fixed piecewise spaceconversion
added piecewise addition test
Added manipulate examples
started docs
split out PiecewiseSpace
Added ivp
Removed DomainSpace
ChebyshevSpace -> Chebyshev
UltrasphericalSpace->Ultraspherical
ChebyshevDircihletSpace->ChebyshevDirichlet
JacobiWeightSpace->JacobiWeight
JacobiSpace->Jacobi
FourierSpace->Fourier
LaurentSpace->Laurent
TaylorSpace->Taylor
HardySpace->Hardy

Removed IFun
Merge pull request #90 from ApproxFun/feat-rename-spaces

Feat rename spaces
Started ArraySpace