Add note to README explaining my changes to this fork.
Fix for differences with my PostgreSQL database.

My database has table column names in all lower case.
Additionally, Ruby was throwing errors about the type column clashing
with its own internal one.
Properly handle the email content types.

Instead of guessing whether something is HTML, look at the message's
content type to do it correctly. Also handle quoted-printable
encoding.
Handle merges properly by finding transactions from related tickets.

This relies on the fact that the effectiveid is changed for a ticket
once merged. We use a custom SQL query to find all transactions
including those from tickets merged in to the current one. This
presents it as a single ticket in Redmine which is neater than the
duplicates approach.

Also skip tickets which have been merged in to another, because
they'll be dealt with by the above SQL query when the ticket they've
been merged in to has been processed.
Use "RT#" rather than "RT ID" as the custom field. Also deal with merges.

When tickets are merged there'll only be one Redmine ticket. But
we record all the original RT ticket numbers in the custom field.
Handle Creates correctly when merging tickets.

The Create transaction is used for the issue description in Redmine.
But when we have multiple tickets merged together we need to deal
with the fact there are multiple Create transactions. Solution is
to use the first as the description and the rest as just normal
messages.
Workaround odd bug that resulted in the ticket linking with merges not working.

Although I'm not using this feature anymore, I did notice the if
statement was never true even when it should be.  Evaluating this
statement before doing it made it work the way it should do.
Some more local changes.

- We're not interested in having the RT ticket ID in the subject.
- We don't used the started date in tickets so remove it instead
  of having a junk date.
- We don't want issue IDs matching old RT IDs - they can start at
  1 again. This compresses the number space after all the deleted
  tickets are ignored.
- Also don't care about ticket owners, or changes in owner.
Allow mapping of email address to other email addresses.

This gives the ability to combine the activity of RT users in to a
single Redmine account.
Looks like attachment.filename is sometimes set to blank.

This causes failures later on because a file can't be created with
no filename.
Set password to 30 random chars for new accounts.