Throw DomainError for out-of-domain evaluation

[jishnub]

This PR changes ArgumentError to DomainError when ChebyshevT is evaluated outside the domain.

julia> x = ChebyshevT([0,1]);

julia> x(2)
ERROR: DomainError with 2:
evaluation point must lie in [-1..1]
[...]

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.13% 🎉

Comparison is base (8ed70d8) 75.51% compared to head (49e1230) 75.64%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #538      +/-   ##
==========================================
+ Coverage   75.51%   75.64%   +0.13%     
==========================================
  Files          38       38              
  Lines        3998     3999       +1     
==========================================
+ Hits         3019     3025       +6     
+ Misses        979      974       -5     

Files Changed	Coverage Δ
src/polynomials/chebyshev.jl	93.64% <100.00%> (+0.03%)	⬆️

... and 1 file with indirect coverage changes

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[jverzani]

Thank you!