Support older versions of BlockArrays and BlockBandedMatrices

Author: jishnub

Project.toml

@@ -28,8 +28,8 @@ Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 AbstractFFTs = "0.5, 1"
 Aqua = "0.8"
 BandedMatrices = "0.17.18, 1"
-BlockArrays = "1"
-BlockBandedMatrices = "0.13"
+BlockArrays = "0.16.26, 1"
+BlockBandedMatrices = "0.12, 0.13"
 Calculus = "0.5"
 Combinatorics = "1.0.2"
 DSP = "0.7.4"