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_PedestalTrackingPixelHistogram.hpp

@@ -153,9 +153,13 @@ void define_pedestal_tracking_pixel_histogram_bindings(py::module &m) {
              Args:
                  file_path: Path to the file to fill from
                  max_frames: Maximum number of frames to fill from the file (default: -1)
+                 reader_threads: Number of parallel file reader workers (default: 2)
+                 reader_chunk_size: Frames claimed by each reader worker per batch (default: 4)
              )",
              py::call_guard<py::gil_scoped_release>(), py::arg("fname"),
-             py::arg("max_frames") = -1, py::arg("verbose") = false)
+             py::arg("max_frames") = -1, py::arg("verbose") = false,
+             py::arg("reader_threads") = std::size_t{2},
+             py::arg("reader_chunk_size") = std::size_t{4})
         .def("process_pedestal_file",
              &PedestalTrackingPixelHistogram::process_pedestal_file,
              R"(