CRAN release 0.24.0

This release contains user-facing changes that include new features and several bug fixes.

stockSymbols() now uses the NASDAQ FTP site instead of downloading the CSV from the NASDAQ stock screener page. runPercentRank(x, n, cumulative = TRUE) now sets observations in the initialization period to NA, in order to be consistent with the other running/rolling functions. Added Ehler's Correlation Trend Indicator.

Fixed runMAD() when 'cumulative = TRUE' and the input contained leading NA. This also affected runMedian(). Fixed ZLEMA() so it wouldn't crash when 'ratio = 0.0' and 'n' was not specified. WMA() now returns an xts object when passed an xts object for 'x' that had leading NA, with the default 'wts = 1:n'. Fixed stoch() when 'bounded = FALSE'. Fixed HMA() so it does not error when 'n' is an odd number.

See the CHANGES file for details.