New Features

Formatters

• comma_format(), percent_format() and unit_format() gain new arguments:
  accuracy, scale, prefix, suffix, decimal.mark, big.mark
  (@larmarange, #146).

• dollar_format() gains new arguments: accuracy, scale, decimal.mark,
  trim (@larmarange, #148).

• New number_bytes_format() and number_bytes() format numeric vectors into byte
  measurements (@hrbrmstr, @dpseidel).

• New number_format() provides a generic formatter for numbers (@larmarange, #142).

• New pvalue_format() formats p-values (@larmarange, #145).

• ordinal_format() gains new arguments: prefix, suffix, big.mark, rules;
  rules for French and Spanish are also provided (@larmarange, #149).

• scientific_format() gains new arguments: scale, prefix, suffix, decimal.mark,
  trim (@larmarange, #147).

• New time_format() formats POSIXt and hms objects (@dpseidel, #88).

Transformations & breaks

• boxcox_trans() is now invertible for x >= 0 and requires positive values.
  A new argument offset allows specification of both type-1 and type-2 Box-Cox
  transformations (@dpseidel, #103).

• log_breaks() returns integer multiples of integer powers of base when finer
  breaks are needed (@ThierryO, #117).

• New function modulus_trans() implements the modulus transformation for positive
  and negative values (@dpseidel).

• New pseudo_log_trans() for transforming numerics into a signed logarithmic scale
  with a smooth transition to a linear scale around 0 (@lepennec, #106).

Minor bug fixes and improvements

• scales functions now work as expected when it is used inside a for loop. In previous
  package versions if a scales function was used with variable custom parameters
  inside a for loop, some of the parameters were not evaluated until the end
  of the loop, due to how R lazy evaluation works (@zeehio, #81).

• colour_ramp() now uses alpha = TRUE by default (@clauswilke, #108).

• date_breaks() now supports subsecond intervals (@dpseidel, #85).

• Removes dichromat and plyr dependencies. dichromat is now suggested
  (@dpseidel, #118).

• expand_range() arguments mul and add now affect scales with a range of 0
  (@dpseidel,
  ggplot2-2281).

• extended_breaks() now allows user specification of the labeling::extended()
  argument only.loose to permit more flexible breaks specification
  (@dpseidel, #99).

• New rescale() and rescale_mid() methods support dist objects (@zeehio, #105).

• rescale_mid() now properly handles NAs (@foo-bar-baz-qux, #104).