mod_sasl2_fast: Fix harmless off-by-one error (invalidates existing tokens!) Problem: This was causing the key to become "<token>--cur" instead of the expected "<token>-cur". As the same key was used by the code to both set and get, it still worked. Rationale for change: Although it worked, it's unintended, inconsistent and messy. It increases the chances of future bugs due to the unexpected format. Side-effects of change: Existing '--cur' entries will not be checked after this change, and therefore existing FAST clients will fail to authenticate until they attempt password auth and obtain a new FAST token. Existing '--cur' entries in storage will not be cleaned up by this commit, but this is considered a minor issue, and okay for the relatively few FAST deployments.

A module providing a streaming statistics interface like
[mod_statistics] but based on the new [statistics API][doc:statistics]
introduced in Prosody 0.10.

# Usage

To use, enable the built-in statistics like so:

```lua
statistics = "internal"
```

Then, in `modules_enabled`, replace `"statistics"` with
`"statistics_statsman"` and the various `"statistics_<something>"`
with equivalent `"measure_<something>"`.


# Compatibility

  ------- --------------------
  trunk   Does not work [^1]
  0.11    Should work
  0.10    Should work
  ------- --------------------

[^1]: not after
    [5f15ab7c6ae5](https://hg.prosody.im/trunk/rev/5f15ab7c6ae5)