Now using right-adjustment for column cells.
updated Command.before_parse() signature and error messages in GRID command parser.
implemented error-origin for ParseError class.
added _OneMeshCommand class and implemented CTRIA3 writing (issue #3).
updated error messages in CTRIA3 parsing.
moved skipping of whitespace to beginning of while-loop.
fixed error with leading empty line.
Command.write_output() now accepts an instance of the new WriteSession class instead of a CommandWriter instance. The CommandWriter can be accessed via WriteSession.writer.
renamed “format” variable to “handler”. writefp() now has a different return value
resolves issue #6. added “options” parameter to FormatHandler.parse_file(), read() and readfp(). The options are now present in the BaseSession (and therefore in ParseSession and WriteSession). The `parser.commands.tolerant` option is now treated in FormatHandler.parse_file().