NAME
	Open -- Open a file for input or output

    SYNOPSIS
	file = Open( name, accessMode )
	D0	     D1    D2

	 BPTR Open( STRPTR,  LONG)

    FUNCTION
	The named file is opened and a file handle returned.  If the
	accessMode is MODE_OLDFILE, an existing file is opened for reading
	or writing. If the value is MODE_NEWFILE, a new file is created for
	writing. MODE_READWRITE opens a file with an shared lock, but
	creates it if it didn't exist.  Open types are documented in the
	< sc:include/dos/dos.h> or < libraries/dos.h> include file.

	The 'name' can be a filename (optionally prefaced by a device
	name), a simple device such as NIL:, a window specification such as
	CON: or RAW: followed by window parameters, or "*", representing the
	current window.  Note that as of V36, "*" is obsolete, and CONSOLE:
	should be used instead.

	If the file cannot be opened for any reason, the value returned
	will be zero, and a secondary error code will be available by
	calling the routine  IoErr().

    INPUTS
	name	   - pointer to a null-terminated string
	accessMode - integer

    RESULTS
	file - BCPL pointer to a file handle

    SEE ALSO
	 Close(),  ChangeMode(),  NameFromFH(),  ParentOfFH(),  ExamineFH()