REM Command (For BASIC Comments)

Before continuing with highlighting errors in the edit box, I noticed (when implementing the routine that converts the token contents to text for display in the program view) that the Remark token type was not actually being used.  The parser is handling two types of remarks, the REM command and the single quote comment method, which is treated as an operator since it can appear at the end of any line and does not need to be preceded by the colon statement separator.

However, these two tokens (REM command and REM operator) were not being handled in the translator.  The REM command token was returning a "Not Yet Implemented" error message.  For the REM command token to be handled and not return this error message, the REM code in the table needed to be assigned a token mode.  It turned out that the specific token mode assigned was not important as long as it wasn't the default NULL token type, which triggers the error message, because the REM command will always be the last command on a line.

To process the REM command token, a new REM command handler was implemented that simply adds the REM command token (which contains the actual comment text in the string of the token) to the RPN output list.  A new translator test (#15) was added for various REM command tests.  The REM operator token is a little trickier to handle, which will be implemented next.

[commit 258f3a9df0]