Added function to scrape .csproj paths from *.sln

Added function to scrape file paths of .csproj project file from a
Microsoft Visual Studio *.sln Solution file. This is a step towards
implementing issue #3.
Added function to find filepath in .csproj by name

Added function to find a filepath in a Microsoft Visual Studio C#
Project (.csproj) file, given the base filename. The current algorithm
takes the first match it finds. This is a step towards implementing
issue #3.
Completed initial implementation for C# project

As such, this closes #3