Korapclient

- Fix DESCRIPTION file.

- Further minimization of tests to make CRAN happy.
- Make authors and maintainers machine readable.

- Further minimization of tests to make CRAN happy. Safety shouldn't suffer.
- Make license specification github and CRAN compliant.

- Fixed many typos.
- Removed redundant and too long running tests.

- Initial release on CRAN.
- Merge highcharter branch providing the new helper function `hc_freq_by_year_ci`.
- Fix reporting cached results in verbose mode.
- Add demo for comparing frequencies in spoken vs. written virtual corpora. See `demo("writtenVsSpoken")`
- Don't invalidate cache on patch level increments.