If a command returns SHELLMATTA_CONTINUE all received data is passed to this command until it returns != SHELLMATTA_CONTINUE or a cancel is received
The data is passed stdin like and can be read byte by byte vie shellmatta_read
The stdin buffer is overwritten witch each new char
now the input string is kept intact until the end of the input is reached
this enables the history buffer to store the complete command
Still broken:
history buffer with heredoc wont execute because the delimiter is not determined correctly
editing of multiline things
