Add `graphflood`

[ktlenz]

Description is a work in progress

Implementation should wait for the GRIDobj

The implementation of graphflood.R requires a wrapper to libtt's graphflood_full.c function with the following arguments:

• [output] hwout (float, dims[0] x dims[1])
• [input] Z (float, dims[0] x dims[1])
• [input] hwin (float, dims[0] x dims[1])
• [input] BCs (uint8_t, dims[0] x dims[1])
• [input] Precipitations (float, dims[0] x dims[1])
• [input] manning (float, dims[0] x dims[1])
• [input] dim (uint, 2)
• [input] dt (float, 1)
• [input] dx (float, 1)
• [input] SFD (bool, 1)
• [input] D8 (bool, 1)
• [input] N_iterations (uint, 1)
• [input] step (float, 1)

Further information

• libtt's API documentation: https://topotoolbox.github.io/libtopotoolbox/api.html
• tt3's implementation: https://github.com/TopoToolbox/topotoolbox3/pull/100/files