Added new option --inject=KEY[,KEY...]

If you have a typed metadata key which contains an amount, you can use
--inject=KEY to inject a posting with that amount wherever a match
occurs.  There are two main forms of usage:

  2010-06-18 Sample
      ; Key:: $100
      Expenses:Food                $100.00
      Assets:Checking

The command would be:

  ledger reg --inject=Key

In the above, transactional form, a posting under the account "Key" will
be injected before the first posting reported for this transaction.
It's amount will be $100.  This only happens once for the whole
transaction.

It is also possible to associate the key with a posting:

  2010-06-18 Sample
      Expenses:Food                $100.00
      ; Key:: $100
      Assets:Checking

Now the injected posting is generated whenever that particular post is
reported.

1 files changed, 0 insertions, 0 deletions

diff --git a/test/baseline/opt-inject.test b/test/baseline/opt-inject.test
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/test/baseline/opt-inject.test