added oro.nifti,tractor.base as per Such packages cannot be required …

…to check the package: any tests which use them must be conditional on the presence of the package. (If your tests use e.g. a dataset from another package it should be in ‘Suggests’ and not ‘Enhances’.) from https://cran.r-project.org/doc/manuals/r-release/R-exts.html#Package-Dependencies

DESCRIPTION

@@ -11,8 +11,13 @@ Authors@R: c(person("Jon","Clayden",role=c("cre","aut"),email="code@clayden.org"
              person("Jean-loup","Gailly",role="cph"),
              person("Mark","Adler",role="cph"))
 Imports: Rcpp (>= 0.11.0)
-Suggests: testthat (>= 0.11.0), covr, reportr, shades
-Enhances: oro.nifti, tractor.base
+Suggests: 
+    testthat (>= 0.11.0),
+    covr,
+    reportr,
+    shades,
+    oro.nifti,
+    tractor.base
 LinkingTo: Rcpp
 Description: Provides very fast read and write access to images stored in the
     NIfTI-1 and ANALYZE-7.5 formats, with seamless synchronisation between