common v1.0.3

common 1.0.3

• Added file.find() function to look for files on the file system.
• Added dir.find() function to look for directories on the file system.
• Added find.names() function to look for variable names on a data frame.
• Added copy.attributes() function to copy column attributes from
  one data frame to another.
• Added supsc() and subsc() functions to get UTF-8 superscript and subscript
  codes from normal characters.
• Fixed bug on v() function when first item had more than one part.
• Fixed bug on sort.data.frame() that was causing it to lose column attributes.
• Restructured test and code files.
• Improved documentation.