merge: trivial fixes

 * rename MENU_POST to MENU_POSTPONE
 * imap: rename the command response constants
 * add more Context checks
 * add Context checks to status_format_str()
 * define flags for mutt_pattern_comp()
 * remove unnecessary goto/label
 * reorder params in driver_tags_get_transformed_for()
 * move data/structs to beginning
 * boolify some variables
 * rename mutt_menu_destroy()
 * rename ParameterList variables
 * fix parameter usage of calloc()
 * hcache: unify naming in free()
 * tidy pre-processor defs
 * refactor pre-processor
 * docs: rename mutt to neomutt
 * Update autocrypt keyring documentation
 * Clean up the autocrypt doc a bit more
 * tidy some comments/whitespace