Merge pull request #399 from davidcarslaw/feat/add-colours

feat: add new colours, fixes, and error catching to `openColours()`

NEWS.md

@@ -4,6 +4,15 @@
 
 - add `calm.thresh` as an option to `windRose`. This change allows users to set a non-zero wind speed threshold that is considered as calm.
 
+- Added new features for `openColours()`:
+
+    - Added new qualitative colour palettes: the "tol" family are colour-blind friendly palettes based on the work of Paul Tol (<https://personal.sron.nl/~pault/>), and "tableau" and "observable" provide access to the "Tableau10" and "Observable10" palettes to aid in consistency with plots made in those platforms.
+
+    - When `n` isn't defined for a qualitative palette (e.g., "Dark2"), the full qualitative palette will be returned. Previously this errored with the default of `100`.
+
+    - `openColours()` will now check whether the provided `scheme` is either a known scheme name *or* a vector of valid R colours, and provide an informative error if this is not the case.
+
+
 ## Bug fixes
 
 - Fixed an issue wherein `importUKAQ()` would drop sites if importing from `local` sites *and* another network.