More changes for support of deserialized modules. Cache files can be given on command line (e.g. Prims.cache instead of prims.fst). Cache files are written in dir FSTAR_HOME/cache. A temporary (until the feature is complete) command line switch --serialize_mods. A dummy serialization module for boot test case (syntax for JSON serialization in ssyntax.fs is F# specific).
merge and conflict resolution in options.fs