Emacs plugin broken since #1290

[fblanqui]

Emacs plugin broken since the merge of #1290: [jsonrpc] Server exited with status 11.

[Alidra]

This problem is related to the presence of an index DB file encoded using the old schema of the indexing DB of Lambdapi (usualy ~/.LPSearch.lb).
PR #1490 will fix this issue. In the meanwhile, moving/deleting or regenerating this file can workaround this issue.