v0.16.4

RegularizedLeastSquares v0.16.4

Diff since v0.16.3

Merged pull requests:

• State-based multi-threading (#90) (@nHackel)
• Documentation Update (#92) (@nHackel)

Closed issues:

• CGNR relTol keyword expects Float64 (#54)
• Is CUDA supported? (#64)
• TV regularization with different lambdas for different parts of x (#89)