When we don't have an actual terminal in ncdirect, return
placeholder 80x24 for ncdirect_dim_y()/ncdirect_dim_x(), but
don't go querying e.g. a redirected file for its dimensions.
Similarly, only request info about cursor position from a true
TTY (we're otherwise likely to hang, or at best get meaningless
data). Rewrite 'direct' PoC to use ncdirect_dim_*().
Add tty_emit(). Closes#752.
* Some things go to the FILE* we're provided. Some can only go to a controlling terminal. Check to see if the FILE we're given is a TTY. If not, open up /dev/tty #752.
* term_emit(): fflush() can return EAGAIN. Loop on it to eliminate a rare error on shutdown that particularly affected unit tests (where we start and shut down Notcurses many times in a row).
* sgr poc: check return value of setlocale()
* drone: run all unit tests
* CMake: add some tests using PoCs
* ncneofetch: print even small palettes
sometimes when we call fflush(ttyfp), we get EAGAIN. we can
loop on this and force the flush. without it, we (fairly rarely)
get errors on shutdown, sometimes manifesting as unit test
failures (especially in the rust wrappers). #742
in ncdirect_render_image(), we want to emit newlines if and
only if we did not hit the right border. we want to emit
cuds (cursor downs) if and only if we've hit the bottom
border. this resolves all mysteries of blank lines, eliminating
a FIXME. it also fixes ncneofetch's image display on very
wide terminals. closes#756. also removes the display semaphore
in ncneofetch, using a more natural pthread_join().
Use ctermid(3) to identify the controlling terminal device.
When one exists, open(2) it up, and retain this file descriptor
across the life of the ncdirect context. Allow a failure, since
not everything requires such an fd. This will be used for tty-
specific activity such as ioctl()s and escape sequences
involving terminal replies (such as get absolute cursor
position). #752
