Improve X11 selection data transfer (INCR) protocol (#451)

This improves reading large selections and fixes one more bug.

- Fix reading selection data size of clients that don't send the size.
  These clients don't respect the ICCCM. Using a default size instead.

- Improve memory allocation by pre-allocating at least 4 MB and
  extending by 4 MB to reduce the number of realloc() operations.
  This may waste up to 4 MB buffer space but this is only an issue
  if clients don't send an appropriate size (see above).

- Limit the initial allocation to 200 MB in case clients send higher
  values. This is very unlikely and might be a bug in these clients.
  Default extension as above would apply anyway.

- Add more comments and optional debug statements (commented out).

Note: reading selections (clipboard) from other clients using the
  INCR protocol is implemented but the opposite (providing large
  selections (clipboard) by using the INCR protocol is not.

0 files changed, 0 insertions, 0 deletions