v0.3.0: graphene G+2D coefficient set

Adds graphene_g_2d_lee2012(): the G + 2D pair of monolayer graphene, expressing the vector decomposition of Lee, Ahn, Shim, Lee and Ryu, Nat. Commun. 3, 1024 (2012) as a linear inversion. Strain axis: -23.5 cm^-1 per percent of randomly oriented uniaxial strain with the measured 2D/G slope 2.2 +/- 0.2; hole-doping axis: the measured slope 0.70 +/- 0.05.

Unit honesty, on purpose: the doping output of this set is the G-band shift attributable to hole doping (cm^-1), not a carrier density. The graphene G-mode doping response is nonlinear and sign-dependent, so no universal linear per-density rate exists to ship; the docstring points to the gated calibrations (Froehlicher and Berciaud, Phys. Rev. B 91, 205413 (2015)) needed for a substrate-specific conversion.

Tests lock every constant to its source, verify the decomposition roundtrip exactly, verify that pure-strain and pure-doping trajectories decompose to zero of the other cause, and assert the noise amplification closed forms (the raw condition number of this set is an artifact of the mixed units; the docstring explains).

Install: pip install ramansep