[Breaking] Change of cone abbreviations for SDP and SOS solvers

[tcunis]

With the latest commit (PR #37), the abbreviations to specify cones for SDP (conic, sdpsol) and SOS (sossol, qcsossol) have been changed. The old abbreviations will lead to an error.

The currently supported cones and their abbreviations are:

1. Convex cones of scalars, vectors, and vectorized matrices in casos.conic and casos.sdpsol:

• lin (previously l): element-wise inequalities
• lor (previously q): Lorentz (quadratic, second-order) cone
• rot (previously r): Rotated Lorentz cone (not yet implemented for SCS)
• psd (previously s): Cone of positive semi-definite matrices

2. Polynomial cones in casos.sossol and casos.qcsossol:

• lin (previously l): coefficient-wise inequalities (reduces to element-wise inequalities for entries of degree zero)
• sos (previously s): cone of sum-of-squares polynomials (relax to PSD)

You can query the supported cones for any solver by calling print_options on the solver object.