Translate in_region into Lua.

Rename “end” member of Region to “finish” not to conflict with Lua
keyword.
Translate draw_end_of_line and draw_line into Lua.
Expand transient_mark_mode into its callers.
Rewrite calculate_highlight_region in Lua, which required head_wp and
cur_wp to have C accessors, and various other utility functions to be
translated into Lua.
Simplify tab_width (copy from master).
Translate draw_width, get_variable_bp and tab_width into Lua.
Update std.lua from stdlib.
Replace calls to non-existent point_copy with calls to table.clone.
Initialise Point properly in point_new.
Update std.lua.
Fix lack of initialisation.
Translate make_mode_line_flags and calculate_start_column into Lua.
Translate draw_status_line into Lua, hence also get_goalc_bp, thisflag
and lastflag (adding C accessors for the two variables).
Finish translation of term_redisplay.c into Lua with term_redisplay
and term_full_redisplay.
Merge changes from head (no changes).
Merge changes from head.
Make some functions local now that entire module is in Lua.
Rewrite minibuf_refresh in Lua.
Add Lua file missing from last commit.
Remove macro_delete in preparation for translation into Lua.