bump x.y.z version to even y prior to creation of RELEASE_3_21 branch

Author: A Wokaty

DESCRIPTION

@@ -1,7 +1,7 @@
 Package: structToolbox
 Type: Package
 Title: Data processing & analysis tools for Metabolomics and other omics
-Version: 1.19.2
+Version: 1.20.0
 Authors@R: c(
     person(
         c("Gavin","Rhys"),