Read a line of characters up to the next newline character or buf.length-1 characters.
If the newline character is encountered, then it will be included in the buffer buf. The buffer will be
null terminated.
| this |
a StreamBuffer object |
| buf |
Memory to write the string to. |
| cancellable |
optional Cancellable object, or null |
| max |
Maxmimum number of characters to store. |
|
the number of characters read, or 0 for end of file, and -1 on error. |