Mbox local mailbox type

This file contains code to parse 'mbox' and 'mmdf' style mailboxes.

Data	Description
MxMboxOps - Mbox Mailbox	Implements MxOps
MxMmdfOps - MMDF Mailbox	Implements MxOps

Function	Description
mbox_ac_add()	Add a Mailbox to an Account - Implements MxOps::ac_add()
mbox_ac_owns_path()	Check whether an Account owns a Mailbox path - Implements MxOps::ac_owns_path()
mbox_adata_free()	Free the private Account data - Implements Account::adata_free()
mbox_adata_get()	Get the private data associated with a Mailbox
mbox_adata_new()	Create a new MboxAccountData struct
mbox_has_new()	Does the mailbox have new mail
mbox_lock_mailbox()	Lock a mailbox
mbox_mbox_check()	Check for new mail - Implements MxOps::mbox_check()
mbox_mbox_check_stats()	Check the Mailbox statistics - Implements MxOps::mbox_check_stats()
mbox_mbox_close()	Close a Mailbox - Implements MxOps::mbox_close()
mbox_mbox_open()	Open a Mailbox - Implements MxOps::mbox_open()
mbox_mbox_open_append()	Open a Mailbox for appending - Implements MxOps::mbox_open_append()
mbox_mbox_sync()	Save changes to the Mailbox - Implements MxOps::mbox_sync()
mbox_msg_close()	Close an email - Implements MxOps::msg_close()
mbox_msg_commit()	Save changes to an email - Implements MxOps::msg_commit()
mbox_msg_open()	Open an email message in a Mailbox - Implements MxOps::msg_open()
mbox_msg_open_new()	Open a new message in a Mailbox - Implements MxOps::msg_open_new()
mbox_msg_padding_size()	Bytes of padding between messages - Implements MxOps::msg_padding_size()
mbox_open_readonly()	Open an mbox read-only
mbox_open_readwrite()	Open an mbox read-write
mbox_parse_mailbox()	Read a mailbox from disk
mbox_path_canon()	Canonicalise a Mailbox path - Implements MxOps::path_canon()
mbox_path_is_empty()	Is the mailbox empty - Implements MxOps::path_is_empty()
mbox_path_parent()	Find the parent of a Mailbox path - Implements MxOps::path_parent()
mbox_path_pretty()	Abbreviate a Mailbox path - Implements MxOps::path_pretty()
mbox_path_probe()	Is this an mbox Mailbox? - Implements MxOps::path_probe()
mbox_reset_atime()	Reset the access time on the mailbox file
mbox_test_new_folder()	Test if an mbox or mmdf mailbox has new mail
mbox_unlock_mailbox()	Unlock a mailbox
mmdf_msg_commit()	Save changes to an email - Implements MxOps::msg_commit()
mmdf_msg_padding_size()	Bytes of padding between messages - Implements MxOps::msg_padding_size()
mmdf_parse_mailbox()	Read a mailbox in MMDF format