[check_swatinit] Cells flagged as UNKNOWN

This is a dataframe snip where some cells have been classified as UNKNOWN, due to SWAT being approximately equal to SWATINIT. This should probably be categorized as PC_SCALED, but the difference between SWAT and SWATINIT is a little too large to uncritically assume they are equal (and what should be tolerance?)

```
I J K X Y Z VOLUME GLOBAL_INDEX PERMX PORO NTG SATNUM EQLNUM FIPNUM SWL SWATINIT SWLPC PCW PPCW SWAT PRESSURE PCOW_MAX Z_DATUM PRESSURE_DATUM OIP_INIT OWC PORV PC_SCALING SWATINIT_SWAT SWATINIT_SWAT_WVOL QC_FLAG PC
291187 122 162 43 486301.979135 6.829820e+06 3656.905762 2618.914988 2960666.0 1386.720947 0.205573 1.0 1 2 2 0.108680 0.301594 0.108680 10.405046 10.405046 0.301583 630.89860 8.82698 3660.0 631.14 0 3664.0 538.378777 1.178778 0.000010 0.005503 UNKNOWN 0.135648
```

The tolerance is currently set to 1e-6. To cover all UNKNOWN cells in the datamodel where this is found (and where it looks like PC_SCALED is the correct flag), the tolerance must be bumped to 1e-3.