Merge pull request #150 from RichardLake/master

Some performance improvements with large stories and a fix for connector lines at high zoom levels.
Merge pull request #151 from RichardLake/master

Some more performance improvments.
Exclude images from the Proofing Copy RTF, they appear as large
unreadable blobs of base64 text.
Merge pull request #152 from greyelf/proofing_copy

Exclude embedded images from the Proofing Copy RTF
Fixes #57 - a least on windows. Can someone else check the other supported operating systems?