Support non-UTF-8 charsets

[Bumsu Hyeon]

I tried to open csv file in 'CP949' encoding(korean) and result was only:

Error in .subset2(x, i, exact = exact) : 
  attempt to select less than one element in get1index

So, I dug into the source code and found that default encoding is hard-coded to 'UTF-8'. Support for encoding selection is required because ms excel-created files use various charsets for non-english characters. And I think it will be more useful if encoding detection is also available.

[Graham Williams]

Thanks for the suggestion. It would certainly be a good idea. If there is any example code that does this it would facilitate the update.

Regards, Graham