Yet another RK scheme

Addition of a new IMEX RK scheme, thanks to @brownbaerchen (#9)

Node-to-node formalism

• definitive structure and test for the node-to-node (N2N) formulation
• N2N form can be used for $Q$ and $Q_\Delta$ coefficients similarly
• started tutorials

Reaching maturity

• finalized a proper design for $Q_\Delta$ generators, with some additional safety checks
• minor improvement on docs

Bugfixes 5

Almost there ...

Bugfixes 4

Show must go on !

Bugfixes 3

jamais deux sans trois !

Bugfixes 2

obviously not better than the first episode ...

Bugfixes

a.k.a I'm dumb ...

pySDC minor adapt

added tLeft and tRight options to the Collocation generator, used by the base Collocation class in pySDC (even if in practice, it's always [0, 1])

pySDC ready

• finished integration of all RK schemes from pySDC, thanks @brownbaerchen
• simplified handling of hCoeffs in RK schemes
• improved dev documentation to add new RK schemes
• fixed notebook test with latest dependencies