send-email: Fix %config_path_settings handling

cec5dae (use new Git::config_path() for aliasesfile, 2011-09-30) broke the expansion of aliases. This was caused by treating %config_path_settings, newly introduced in said patch, like %config_bool_settings instead of like %config_settings. Copy from %config_settings, making it more readable. While at it add basic test for expansion of aliases, and for path expansion, which would catch this error. Nb. there were a few issues that were responsible for this error: 1. %config_bool_settings and %config_settings despite similar name have different semantic. %config_bool_settings values are arrays where the first element is (reference to) the variable to set, and second element is default value... which admittedly is a bit cryptic. More readable if more verbose option would be to use hash reference, e.g.: my %config_bool_settings = ( "thread" => { variable => \$thread, default => 1}, [...] %config_settings values are either either reference to scalar variable or reference to array. In second case it means that option (or config option) is multi-valued. BTW. this is similar to what Getopt::Long does. 2. In cec5dae (use new Git::config_path() for aliasesfile, 2011-09-30) the setting "aliasesfile" was moved from %config_settings to newly introduced %config_path_settings. But the loop that parses settings from %config_path_settings was copy'n'pasted *wrongly* from %config_bool_settings instead of from %config_settings. It looks like cec5dae author cargo-culted this change... 3. 994d6c6 (send-email: address expansion for common mailers, 2006-05-14) didn't add test for alias expansion to t9001-send-email.sh Signed-off-by: Cord Seele <cowose@gmail.com> Tested-by: Michael J Gruber <git@drmicha.warpmail.net> Signed-off-by: Jakub Narebski <jnareb@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>