clear all deprecated elements before calling it abi3

[dankamongmen]

There's been a good deal of deprecated material collecting, which we can't remove until ABI3, intended to be marked by 3.0.0.

I've been trying to move it to the bottom of notcurses.h and ncdirect.h, but we ought do a final pass.

All shipped code ought already have moved off of deprecated material, of course.

Also look for anything we can move to a static inline and away from a symbol. Symbols can't be promoted to static inline, or else old programs will stop linking.

a partial list, growing as things change:

• remove renderfile from notcurses_options remove renderfile property from notcurses_option #2081
• convert all notcurses_can_*() functions to static inline wrappers around notcurses_capabilities() add missing capabilities functions to direct mode #1768
• convert all non-inline ncdirect_can_*() functions to static inlines around ncdirect_capabilities() add missing capabilities functions to direct mode #1768
• kill all functions marked as ((deprecated))
• kill old CELL_ALPHA_* definitions
• kill old palette256 type
• notcurses_render_to_buffer(), notcurses_render_to_file()
• notcurses_render() becomes static inline
• nccell_width() is removed
• move fields around in ncstats to match documentation
• remove the unused third parameter from ncdirect_getc() and notcurses_getc() pull sigset_t out of API #1967
• renumber our synthesized NCKEY constants to match the kitty protocol (see take advantage of kitty keyboard protocol #2131)
• ncstrwidth becomes static inline (see add ncstrwidth() that returns column width of valid prefix #2153)
• remove definitions of notcurses_getc() and ncdirect_getc()
• stylemask functions ought return uint16_t (see fixing stylemask related functions parameter & return type #2200)
• ncplane_move_below() and ncplane_move_above() ought be modified to accept NULL, with obvious implications, and ncplane_move_top() and ncplane_move_bottom() can be rewritten as static inlines around them, cutting two symbols
• rename ncplane_pixelgeom to ncplane_pixel_geom
• rename ncplane_moverel to ncplane_move_rel
• change all geometry params and especially returns from int to unsigned
• require ncpile* (from ncplane*) instead of notcurses* for ncvisual_render(), NULL for new pile (ncvisual_render needs be pile-aware #1462)
• notcurses_get() ought take an absolute deadline rather than a delay bound. kill off delaybound_to_deadline() once this is done (see need time against CLOCK_MONOTONIC with musl libc #2302)
• ncdirect_rounded_box() and ncdirect_double_box() ought become static inline
• notcurses_top() and notcurses_bottom() can become static inlines around ncpile_{top, bottom}()
• ncmetric() can become static inline

you know, maybe we don't want to nuke everything that's deprecated; where possible, we could keep them as (deprecated) static inlines, so a recompile still works. maybe.

rejected:

*ncplane_erase() becomes static inline around ncplane_erase_region(), which calls the current internal ncplane_erase() for that special case (it's a good optimization) (dumb idea. this would just require traversing all the checks in ncplane_erase_region() for no good reason)

• notcurses_getvec() can become static inline the whole point of notcurses_getvec() is speed, and we can be faster if we embed this behind the locking

[dankamongmen]

so ought we deprecate notcurses_render()?

[dankamongmen]

we're removing the deprecated notcurses_render_to_file(), but what about ncpile_render_to_file()? are we keeping that?

[joseluis]

adding to the list, in case the pointer types can be normalized:

• ncplane_dim_yx
• ncplane_cursor_yx

[dankamongmen]

adding to the list, in case the pointer types can be normalized:

• ncplane_dim_yx
• ncplane_cursor_yx

these both got done