Add CoKriging support (#22)

* Add CoKriging support

* Minor adjustments in krig.jl

* Fix OrdinaryKriging

* Choose factorization for different geostats functions

* Fix krigmean in multivariate case

* Refactor universal.jl

* More fixes to ordinary and universal Kriging

* Fix external drift Kriging

* Fix typo

* Rename fields of Kriging models

* Add estimation variance in multivariate case

* Cleanup krig.jl

* More refactoring

* More refactoring

* Add estimation variance with covariances

* Add inbounds

* Eliminate ExternalDriftKriging as it is redundant

* Refactor variance units

* Refactor KrigingState

* More refactoring

* More refactoring

* Fix universal.jl

* More refactoring

* Refactor pairwise calls

* More refactoring

* Optimize ordinary.jl

* Optimize universal.jl

* Update compat

* More refactoring

* More refactoring

* Decompose variance contributions

* More refactoring

* More refactoring

* Add krigvar in terms of Transiogram

* Treat scalar variance case

* More fixes to SimpleKriging

* Strip units from predictprob

* Fix krivar for Covariance

* More refactoring

* Update tests

* More refactoring

* More refactoring

* Add tests with Covariance

* Add tests for CoKriging with Variogram

* Fix formatting

* Add tests with transiogram

Project.toml

@@ -21,7 +21,7 @@ Combinatorics = "1.0"
 CoordRefSystems = "0.16"
 Distances = "0.10"
 Distributions = "0.25"
-GeoStatsFunctions = "0.7"
+GeoStatsFunctions = "0.8"
 GeoTables = "1.21"
 LinearAlgebra = "1.9"
 Meshes = "0.47 - 0.52"