v0.9.2

• Fixed bug in direct beam multilayer solver.
• Changed assert-based input checks to if-statements that raise ValueError.
• Added return_tau_arr argument to every output function (tau is the optical depth and tau_arr demarcates the layers in the atmosphere)
• Improved and corrected documentation.
• Added explanatory preamble to each PyTest.

Full Changelog: v0.9.1...v0.9.2