proxyDB error: IDFcosine already in registry

[AdamSpannbauer]

if sentence similarity processing starts and is halted before completion "idfcosine" function not removed from proxy registry. Currently no logic to check if function is already in registry before attempting to push idfcosine in; this produces error.

Add logic to check if idfcosine is in proxydb before adding.. create workaround.. perhaps include onexit logic

[AdamSpannbauer]

added logic to check if function name in pr_DB and append random numbers until name is valid