Windows-specific file listing

[Jellevanderwerff]

On lines 98-107 of server.R probably best to change paste(path, list_of_files[a], sep="\\") within the three read functions to: file.path(path, list_of_files[a]), to make the functions platform-independent (as only Windows uses backslashes).

(sorry could have forked and commited etc., but seemed like too much effort as now everything works for me haha).

[Jellevanderwerff]

Change suggested in #4