Escape '&' in mod list, consistent path separators in exception

[DasSkelett]

Problems

Ampersands (&) in mod names or abstracts in the mod list are currently interpreted as hint to create automatic keyboard shortcuts (visualized through underscores), instead of printing them as literal.
See for example the mod DumpAndBurn, with the name Dump&Burn!:

Error messages of krakens thrown while trying to load the GUIConfig.xml have a mix of / and \ as path seperators on Windows, like:

Unhandled Exception:
CKAN.Kraken: Error trying to parse "c:/program files(x86)/steam/SteamApps/common/Kerbal Space Program/CKAN\GUIConfig.xml": Root element missing.

Changes

The texts in the name, author and abstract are now escaped using && in ModList.MakeRow(). I didn't spot another location where they would need escaping (tested recommendation tab and modpack export tab).

The exception about broken GUIConfig.xml files now gets the path string from a FileInfo object, which should always be formatted consistently and correctly for the user's OS.