Handle every case for strto[ld]

strtol and strtod can try to parse a number from a command line
argument that is an empty string, a string that has characters
other than what numbers have, it can overflow or underflow and
it can be too high or low for a specific use case.
Handle all these cases properly.
Add character options

Add options to choose which characters represents an object alive
and a dead object. This is currently implemented only for ui
without ncurses.

TODO

If possible, only allow the character to be such a character, which
glyph is one character wide. East asian characters can be wider than
others?
Implement commit 23be268 to ncurses_ui

Add choosable object characters to ncurses_ui too. This requires
wide ncurses - ncursesw.