Issue #295: Flags: differentiate between no flag (txn) and * (blais/beancount)

[Martin Michlmayr]

New issue 295: Flags: differentiate between no flag (txn) and *
https://bitbucket.org/blais/beancount/issues/295/flags-differentiate-between-no-flag-txn

Martin Michlmayr:

In ledger, a transaction without a flag means "uncleared" whereas the flag `*` means "cleared" (`!` means pending). So there's a difference between no flag and the * flag.

In a conversion with Ethan Glasser-Camp on how to convert from ledger to beancount, Ethan pointed out that beancount treats "txn" (i.e. no flag) as `*` and that there's no concept in beancount of "no flag".

Is this intentional? It seems weird to me... why have `txn` in the first place when it's the same as `*`?

Example:

```
1900-01-01 open Assets:A
1900-01-01 open Assets:B

2018-05-13 * "Transaction with flag *"
Assets:A 10.00 EUR
Assets:B

2018-05-13 ! "Transaction with flag !"
Assets:A 10.00 EUR
Assets:B

2018-05-13 txn "Transaction with no flag"
Assets:A 10.00 EUR
Assets:B
```

```
bean-doctor context e 13
...
2018-05-13 * "Transaction with no flag"
```

i.e. `txn` becomes `*`.