Starting from current stream location, scan forward over an int. Determine whether it's an integer or not. If so, push the integer characters to the specified CharBuffer. If not, put them in backString (essentially leave the stream as it was) and return false.
If it was an int, the stream is left 1 character after the end of the int, and that character is output in the thisChar parameter.
The formats for integers are: 1, +1, and -1
The + and - signs are included in the output buffer.