Lsl

* Added support for adding/subtracting timedelta instances from FrameTimestamp instances
* Fixed an indexing problem in the coherent dedispersion padding
* Added a `tai_mjd` field to lsl.reader.base.FrameTimestamp
* Fixed a problem downsampling baselines from a lsl.imaging.data.VisibilityDataSet instance
* Added a new `lsl.writer.virtual` module to help convert correlator output into something that can be used with `lsl.imaging.utils`
* Updated the visibility writers to accept integrations with different numbers of baselines
* Added support for 'python -m lsl.version'
* Removed lslTelemetry.py in favor of 'python -m lsl.misc.telemetry'
* Removed maskWisdom.py in favor of 'python -m lsl.misc.wisdom'
* Changed the lsl.correlator.fx.FXMaster polarization keyword from 'Pol' to 'pol'
* Added lsl.misc.file_cache to help with LSL cache management
* Added lsl.misc.file_lock to help with conflicts updating the LSL file caches
* Updated lsl.misc.ionosphere to use the 'unlzw' module to deal with unix compressed files
* Updated LSL to work on read-only filesystems where the configuration/caches cannot be created
* Moved the LSL-specific FFTW wisdom file to ~/.lsl
* Added a new lsl.testing module to help with the test suite
* Updated the test suite to improve coverage and make failures more specific

* Improved compatibility for measurement sets generated by lsl.writer.measurementset
* Added support for directly writing measurement sets with correlateTBF.py, correlateTBN.py, and correlateTBW.py
* Fixed a problem copying AntennaArrays in lsl.imaging.data.VisibilityDataSet
* Fixed a bug in the polarization handling in XEngine3

* Fixed a build problem with lsl/reader/drspec.c found on some versions of OSX
* Various cleanups based on https://lgtm.com analysis
* Fixed a problem in the measurement set writer that caused CASA's listobs() to fail
* Clarified which version of FFTW3 is needed.

* Added UCF_USERNAME_RE to lsl.common.idf/sdf/sdfADP to make it eaiser to validate UCF usernames
* Added support for querying the MCS `mindelays.txt` file in lsl.common.metabundle/metabundleADP
* Added support for the XXCRCIYY, CRCI, and I-only DR spectrometer modes
* Several consistency fixes for the API in lsl.common.sdf/sdfADP and lsl.common.metabundle/metabundleADP

* Fixed a problem with displaying lsl.reader.errors under Python3
* Cleaned up SDF and IDF rendering to make it faster
* Fixed a problem in lsl.imaging.utils.ImgW that lead to a shift in source position with frequency
* Fixed a problem fitting a Gaussian to the point spread function in lsl.imaging.deconv

* Added a -v/--lwasv option to correlateTBN.py and tbnSpectra.py
* Added better input file type checking to the various "correlate" and "spectra" scripts
* Switched back to CDDIS for ionospheric data
* Fixed an error when setting beam/dipole mode for STEPPED SDFs
* Fixed a bug in updateLSLSSMIF.py when trying to revert a SSMIF
* Added a color keyword to the classes in lsl.common.busy and lsl.common.progress
* Added a new BusyIndicatorPlus class to lsl.common.busy
* Added a new DownloadBar class to lsl.common.progress
* Reduced the number of warning messages generated by STEPPED SDFs
* Added automatic updates of leap second information
* Changed the IDF and SDF modules to be more flexible on the styles of input coordinates