DTSg v0.4.0

• Added memoryOverCPU argument to rollapply() method: allows for preferring CPU over memory usage which makes the method more flexible in terms of resource consumption.
• Settings of option DTSgClone in e.g. .RProfile are now respected and not overwritten by TRUE when the package is loaded.
• Fixed useless coercion of POSIXct .dateTime columns to POSIXct upon object creation in case they contained at least one missing value.
• Switched to unit testing framework of the tinytest package instead of the testthat package.
• Slightly improved vignettes and documentation.
• Minor internal code improvements.