Array{SymEngine.Basic,1} dot product

[stefanbringuier]

Added linalgebra.jl which includes proper method(dispatch) for taking Array{SymEngine.Basic,1} (vector) dot product. The method is still bound to LinearAlgebra. This file can serve as a proper place to provide additional SymEngine.jl linear algebra support.

[ranocha]

I think this can be closed since everything works after #233 has been merged:

julia> using SymEngine, LinearAlgebra

julia> v = [ symbols("v_$i") for i=1:4 ]
4-element Vector{Basic}:
 v_1
 v_2
 v_3
 v_4

julia> dot(v, v)
v_1^2 + v_2^2 + v_3^2 + v_4^2