Tolerate slow large-job uploads on small-buffer printers

[boingball]

Summary

• give document-body uploads a 180-second no-progress allowance while retaining the existing short connection, control-message and response timeouts
• distinguish a body-upload stall as error -19 instead of folding it into the generic send failure
• record document bytes sent/total in the debug log and retained status sidecar
• expose the new stall reason in View Spooler
• bump both driver builds to 41.18

Why

In #91, the Canon TS8360 accepts a five-page duplex PWG Raster document but a 36-page document prints only the first page and part of the second. MintPRINT already streams the file in small writes and TCP supplies back-pressure, but driver 41.17 abandons any write which cannot make progress for 20 seconds. A small printer receive buffer can fill during a long raster job while the printer processes a page, creating exactly that pause.

This change keeps the bounded-send protection introduced for genuinely hung printers. It only lengthens the allowed stall for document data; connection setup, IPP headers and the final response remain tightly bounded.

Beta test for #91

1. Install the correct 41.18 driver build and reboot so printer.device unloads the resident 41.17 segment.
2. Enable Debug and print the same 36-page duplex WordWorth document.
3. If it still fails, attach T:MintPRINT-driver.log and the retained .status sidecar. Error -19 plus bytes sent/total will show exactly where the Canon stopped draining the connection.

A View Spooler Retry uses the copy of ipp_client.c linked into MintPrintSettings, so testing Retry specifically requires the beta Settings executable as well as the beta driver. Reprinting from WordWorth tests the driver change directly.

Refs #91.