learnrbook 1.0.2

Package documentation web site at: https://docs.r4photobiology.info/learnrbook/

This is the second version submitted to CRAN for the book as published in the R Series.

This update adds .R files with the code from all chunks in the book, including a few not visible. There are some small edits to the documentation.

NOTE: The updated package is on its way to CRAN.

Please raise issues concerning bugs or enhancements to this package through Bitbucket https://github.com/aphalo/learnrbook-pkg/issues