Merge branch 'ab/send-email-optim'

Merge branch 'ab/send-email-optim'

"git send-email" optimization.

* ab/send-email-optim:
  perl: nano-optimize by replacing Cwd::cwd() with Cwd::getcwd()
  send-email: move trivial config handling to Perl
  perl: lazily load some common Git.pm setup code
  send-email: lazily load modules for a big speedup
  send-email: get rid of indirect object syntax
  send-email: use function syntax instead of barewords
  send-email: lazily shell out to "git var"
  send-email: lazily load config for a big speedup
  send-email: copy "config_regxp" into git-send-email.perl
  send-email: refactor sendemail.smtpencryption config parsing
  send-email: remove non-working support for "sendemail.smtpssl"
  send-email tests: test for boolean variables without a value
  send-email tests: support GIT_TEST_PERL_FATAL_WARNINGS=true