dark cannot handle read-only input files

[wixbot]

I tried dark on a read-only msm and directly happened
upon these two bugs:

cvs diff Decompiler.cs (in directory
C:\Andreas\res\wix\src\wix)

1. Index: Decompiler.cs

RCS file: /cvsroot/wix/wix/src/wix/Decompiler.cs,v
retrieving revision 1.1
diff -r1.1 Decompiler.cs
235c235
< using (this.inputDatabase = new Database

1. (inputPath, OpenDatabase.Transact))

> ```
> using (this.inputDatabase = new Database
> ```
>
> (inputPath, OpenDatabase.ReadOnly))
> 463c463
> ## < summary.Close(true);
>
> ```
> summary.Close(false);
> ```
1. I’m pretty sure that we don’t need transactions when
we’re reading.
2. I’m also pretty sure that we don’t need to save the
summary info either.

Originally opened by zune01 from http://sourceforge.net/p/wix/bugs/2/