Lsl

* Updated to IGRF14

* Fixed DRX8 CI8 support
* Re-enabled DRX8 file detection for lsl.reader.ldp.LWANADataFile
* Updated drxSpectra.py to work with DRX8 files as well

* Added support for OVRO-LWA in IDFs
* Reduced the number of "Cannot download file ..." warning when importing lsl
* Cleaned up uniform and Briggs weighting in the lsl.imaging.utils.ImgWPlus class
* Added missing DRX8 methods to lsl.reader.buffer and lsl.reader.ldp
* Updated lsl.correlator._core.XEngine[23] to work with CI8 data
* Moved drxSpectra, tbfSpectra, and correlateTBF over to use CI8 loading by default
* Improved performance of the TBF reader
* Updated the README and installation notes to say that you need a C++ compiler with C++11 support

* Fixed a problem with applying station dynamic metadata to a LWAStation object
* Make the GloTEC model downloads more granular to help with data transfer sizes
* Compress the GloTEC model after download to reduce disk usage
* Fixed a problem separating TBF from DRX data in the era of multiple TBF flavors
* Fixed a problem identifying COR data in the era of multiple COR flavors

* Enabled caching in lsl.sim.beam to reduce the number of times a model is loaded
* Updated lsl.common.data_access to request file be gzip compressed when downloaded
* Refactored lsl.common.data_access to expose the internal downloader function
* Added better warnings/error messages to lsl.misc.file_cache and lsl.misc.file_lock to help debug stuck locks
* Updated lsl.common.idf to default to using all (full + mini) stations
* Fixed the units on the final report of a DownloadBar run
* Worked on improving the performance of "return_ci8=True" in lsl.reader.ldp

* Fixed a problem with lsl.sim.beam.beam_response/mueller_matrix when scalar azimuth/altitude are provided
* Fixed a problem with lsl.sim.beam.beam_response/mueller_matrix returning NaNa for 'empirical' and 'llfss'
* Updated FrameTimestamp.__float__ to strictly return a float
* Fixed a timestamp problem in lsl.reader.vdif related to tracking leap seconds since the reference epoch