In commit 8ed03baa76 (gitattributes: prefer `eol=crlf` to `-crlf`,
2017-08-23) we left a few CRLF blobs in the repository. Some Git
versions get confused by text files with CRLF blobs. Convert them
to LF blobs. Use the `eol=crlf` attribute to tell Git to use CRLF
on checkout.
Create class cmVisualStudioSlnParser as a generic parser for Visual
Studio .sln files. Implement minimum functionality but keep class
extensible. Add tests for the class.