Improve error message & allow read-only access to a project

[Daniel Weeks]

When trying to do a 'load-pedigree' command on a PLINK/SEQ project my student set up, it died with

error (14) unable to open database file

about the 'inddb' database file. However, this was confusing, as I had write permission on the 'inddb' file.

It looks like the error actually involves not having write permission on the _out folder that contains the inddb and vardb database files, and/or not having write permission on the .pseq file for the project.

It would be nice to improve the error message to be more informative, if possible.

NOTE: Initially I couldn't even run summary statistics on the plnkseq project until I granted myself write permission on the inddb and vardb. This seemed strange to me, as presumably asking to pull data from the PLINK/SEQ project should not require write permission. For use of PLINK/SEQ in a collaborative environment, it would be good to adjust it so that users could pull data from a PLINK/SEQ project without being given write permission. That is safer, as only a subset of people on the project should be given permission to alter the data in a project.