Refactor/vertical normal inputs

[JoshCederstrom]

This PR corrects the coordinate convention for depth inputs so that DEPTHTOBEDROCK, BEDROCKFILE, and GWATERFILE are interpreted as vertical depths rather than slope-normal depths. Previously the outputs could report a depth to water table deeper than the specified depth to bedrock, e.g. a run with a constant 3 m bedrock depth ending with polygons reporting a water table below 3 m.

Technical Changes (C++ / Inputs)

Slope conversion factor (tCNode)

• Added tCNode::getCosSlope(), returning cos(atan(S)) for the node's flow edge, computed as 1/sqrt(1+S^2) to avoid two libm calls. Returns 1.0 when no flow edge is set and is floored at 1E-9.

Depth inputs (vertical → slope-normal at assignment)

• Initial water table from GWATERFILE is multiplied by cn->getCosSlope() in the water table assignment loop. This covers both the gridded and Voronoi-file options, which share the assignment. Without it, an initial water table near bedrock on a steep node would fall below the converted bedrock depth and be silently clamped to bedRock - 1, changing initial storage.
• Depth to bedrock is multiplied by cn->getCosSlope() immediately after it is read, covering both the uniform DEPTHTOBEDROCK and the BEDROCKFILE grid. Applied before the initial Nwt clamp, setBedrockDepth(), the SoilCutoff / RootCutoff calculations, and the initial saturated storage, so all of them pick up the converted value.

Outputs

• WriteIntegrVars() now divides getBedrockDepth() by the node's cos_slope for the Bedrock_Depth_mm column, so the value echoed back matches the vertical depth the user supplied rather than the internal slope-normal value.