libr v1.2.8

• Fixed bug on datastep that sometimes was causing variables to lose their attributes.
• Added "where" parameter to datastep.
• Fix bug on datastep that was causing a single variable dataframe to be returned
  as a vector.
• Cleared rownames on datastep exit.
• Added "MaxChar" column to dictionary to hold the maximum number of characters
  for a data value in the column. This is different from "width" which
  is the user-defined, proscribed width. MaxChar is the actual width with no
  padding.
• Added "rda" engine to libname.
• Allowed single value NSE on drop, keep, and by parameter of datastep().
  For multiple values, use the v() function.
• Added output() function to datastep.
• Improved datastep output column ordering. New variables were coming out
  in the opposite order they were added. Now they are better.
• Added "set" parameter to datastep.
• Added "merge", "merge_by", and "merge_in" parameter to datastep().
• Fixed bug on datastep() rename.
• Added/fixed documentation.
• Updated logo.