Fix formatting of long log messages

[uklotzde]

Fixes #29.

[uklotzde]

Requires HMIProject/open62541-sys#10.

[sgoll]

@uklotzde I published open62541-sys@0.2.2.

[sgoll]

Seems alright. One difference seems to be that for long messages, the previous code would truncate with "…" inside the largest allowed buffer while the current code now bails out early when working on the small buffer, truncating the message at shorter buffer size than necessary.

You can see the difference with

const FORMAT_MESSAGE_DEFAULT_BUFFER_LEN: usize = 10;
const FORMAT_MESSAGE_MAXIMUM_BUFFER_LEN: usize = 100;

I would expect most messages to have 99 characters but most have only 9.