v2.1.0 - Oldenburger 3D Tage

• new dependency: cog for code generation
• cuda: fix 256-bit descriptor size for significant speedup at larger stack sizes
• bicos: support disparities smaller than 0
• cli: remove points with Z < 0, introduce --allow-negative-z
• cuda, cpu: reduce memory usage (by adding another kernel template parameter...)
• lib: be consistent with throwing BICOS::Exceptions inside of the library

Full Changelog: v2.0.0...v2.1.0