FileOpen ( stream, fileName$, mode )

Opens a file.

Modes:
TEXT_INPUT - Open a file for reading text. The file must already exist.
TEXT_OUTPUT - Open a new file for writing text. If the file already exist it will be overwritten.
TEXT_APPEND - Opens a file for appending text to the end of the file.  A file will be created if it doesn't already exist.
TEXT_INPUT_PLUS - Opens a file for reading and writing text.  The file must already exist.
TEXT_OUTPUT_PLUS - Opens a file for both reading and writing.  If the file already exist it will be overwritten.
TEXT_APPEND_PLUS - Opens a file for reading and appending text to the end of the file.

BINARY_INPUT - Open a file for reading binary data. The file must already exist.
BINARY_OUTPUT - Open a new file for writing binary data. If the file already exist it will be overwritten.
BINARY_APPEND - Opens a file for appending binary data to the end of the file.  A file will be created if it doesn't already exist.
BINARY_INPUT_PLUS - Opens a file for reading and writing binary data.  The file must already exist.
BINARY_OUTPUT_PLUS - Opens a file for both reading and writing.  If the file already exist it will be overwritten.
BINARY_APPEND_PLUS - Opens a file for reading and appending binary data to the end of the file.

Returns True if File is Opened and False if File is not opened.