merge: refactor to reduce variable scope

These changes should not affect the behaviour of the code.

 * alias.c
 * attach.c
 * browser.c
 * buffy.c
 * color.c
 * commands.c
 * compose.c
 * conn/getdomain.c
 * conn/socket.c
 * conn/ssl.c
 * conn/ssl_gnutls.c
 * conn/tunnel.c
 * copy.c
 * curs_lib.c
 * curs_main.c
 * doc/makedoc.c
 * filter.c
 * from.c
 * handler.c
 * hdrline.c
 * header.c
 * help.c
 * hook.c
 * imap/auth_cram.c
 * imap/command.c
 * imap/imap.c
 * imap/util.c
 * init.c
 * keymap.c