Support index namespace

[shuding]

From the implementation I don't see why an index is required but not an index namespace. Would be nice to allow that to use an existing index but prevent potential conflicts.

[ytkimirti]

Makes sense, I opened a ticket for this. Thanks for the suggestion

[ogzhanolguncu]

@shuding This is now supported.

[GuiBibeau]

@ogzhanolguncu I see it's indeed supported from the addition in the codebase. However 1.0.3 typedefs don't seem to include the additional field in the constructor of a cache. Is that expected?