#1757 CRLF handling in SCI_COUNTCHARACTERS & SCI_POSITIONRELATIVE

Both these messages are documented as working on "whole characters". It is not mentioned whether CRLF is counted as one or two whole characters.

SCI_COUNTCHARACTERS counts a CRLF sequence as one character
SCI_POSITIONRELATIVE counts a CRLF sequence as two characters

This is problematic because the two messages otherwise complement each other. At the very least, this behavior should be clearly documented.

I use release 3.5.0, but from the sources it seems to be the same in the latest version.

[Neil Hodgson]

SCI_COUNTCHARACTERS comes from [#1133].

[Neil Hodgson]

Fix committed as [8d5e93].