RKorAPClient 0.5.1

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

RKorAPClient 0.5.0

• 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.