FastPedestal + optimizations in the cluster finder (#341)

Optimized pedestal tracking with FastPedestal and performance improvements to the cluster finder. 
- ~2x faster hitting 14k FPS on benchmark dataset on 16 core threadripper pro


**Changes**
- No bounds check on interior of frame. (only within half of a cluster)
(~15% improvement)
- Cache threshold (std*n_rms) Biggest improvement comes from not
computing std for each access
- Cache pedestal subtracted frame
- Switched to FastPedestal which assumes we reached steady state

**Things tried but rejected:**
- Always store cluster values, commit on val==max (~15% drop in frame
rate)

**Options**
- using 16 bit clusters and 16 bit pedestal. (slows down the single
threaded case but allow us to reach 12k with multi threading)

**Other notes on performance**
- Passing in memory frames from python and doing nothing: 0.8us/frame
- Passing + pedestal subtraction: 28us/frame
- Passing + pedestal + cluster finding (no store): 652us/frame
- Passing + pedestal + cluster finding: 886 us/frame

python/src/bind_ClusterFileSink.hpp

@@ -15,8 +15,6 @@
 #include <pybind11/stl_bind.h>
 
 namespace py = pybind11;
-using pd_type = double;
-
 using namespace aare;
 
 #pragma GCC diagnostic push
@@ -29,6 +27,8 @@ void define_ClusterFileSink(py::module &m, const std::string &typestr) {
 
     using ClusterType = Cluster<T, ClusterSizeX, ClusterSizeY, CoordType>;
 
+    // TODO! adapt to set pedestal type (needs templating of ClusterFileSink)
+    // or maybe access through base class?
     py::class_<ClusterFileSink<ClusterType>>(m, class_name.c_str())
         .def(py::init<ClusterFinderMT<ClusterType, uint16_t, double> *,
                       const std::filesystem::path &>())