Actually enhanced __get_cword3 to _get_cword, and removed __get_cword4.
__get_cword4 could handle chars to exclude from COMP_WORDBREAKS, but
failed with partial quoted arguments (e.g. "a 'b c|", | = cursor
position). This was no problem till bash-4.0.35, because bash < 4.0.35
also returned partial quoted arguments incorrectly. See also:
http://www.mail-archive.com/bug-bash@gnu.org/msg06094.html
Now that bash-4.0.35 returns quoted arguments ok, __get_cword3 is
enhanced to also handle chars to exclude from COMP_WORDBREAKS. Because
__get_cword3 also handles partial quoted arguments correctly, this makes
__get_cword3 suitable for bash-4 as well.
Bash < 3.2.41 has a bug where 'history' disappears from SHELLOPTS
whenever a shopt setting is sourced or eval'ed. Disabling 'history'
makes it not show in tests "Environment should not be modified"
for bash < 3.2.41.
Added helper function `is_bash_version_minimal()' to
test/lib/library.sh.
