Pyrtcm

What's Changed
* Rc 1.1.0 by semuadmin in https://github.com/semuconsulting/pyrtcm/pull/57

1. `PRN`, `CELLPRN` and `CELLSIG` attributes added to satellite (NSAT) and cell (NCELL) groups within parsed RTCM3 MSM payloads via `SPARTNMessage._getsatcellmaps()` function, replacing previous `sat2prn()` and `cell2prn()` helper functionality. labelmsm keyword argument signifies either RINEX (1) or Frequency Band (2) signal format for CELLSIG attribute.

**Full Changelog**: https://github.com/semuconsulting/pyrtcm/compare/v1.0.20...v1.1.0

What's Changed
* RC 1.0.20 by semuadmin in https://github.com/semuconsulting/pyrtcm/pull/56

1. Add parse_msm helper method to parse RTCM3 MSM message type into series of iterable data arrays.
1. Add parse_4076_201 helper method to parse RTCM3 4076_201 SSR message types into series of iterable data arrays.
1. Internal streamlining of conditional group parsing & updated docstrings - no functional changes.

**Full Changelog**: https://github.com/semuconsulting/pyrtcm/compare/v1.0.19...v1.0.20

What's Changed
* Rc 1.0.19 by semuadmin in https://github.com/semuconsulting/pyrtcm/pull/55

ENHANCEMENTS

1. Minor internal streamlining of nested group parsing - no functional changes.

**Full Changelog**: https://github.com/semuconsulting/pyrtcm/compare/v1.0.18...v1.0.19

What's Changed
* RELEASE CANDIDATE 1.0.18 by semuadmin in https://github.com/semuconsulting/pyrtcm/pull/54

FIXES:

1. Fixes issue with parsing of IGM05/IGM06 SSR message payloads e.g. 4076_025, 4076_066, etc. Output can be verified using caster products.igs-ip.net:2101/SSRC02IGS1.

**Full Changelog**: https://github.com/semuconsulting/pyrtcm/compare/v1.0.17...v1.0.18

What's Changed
* RELEASE CANDIDATE 1.0.17 by semuadmin in https://github.com/semuconsulting/pyrtcm/pull/53

ENHANCEMENTS:

1. Add proprietary IGS SSR 4076 messages, as defined in https://files.igs.org/pub/data/format/igs_ssr_v1.pdf. NB not fully tested as available NTRIP sources only cover a subset of the 4076 subtypes defined.

**Full Changelog**: https://github.com/semuconsulting/pyrtcm/compare/v1.0.16...v1.0.17

What's Changed
* RELEASE CANDIDATE 1.0.16 by semuadmin in https://github.com/semuconsulting/pyrtcm/pull/49


1. PRN SIG mapping streamlined - id2prnsigmap() helper method replaced by dictionary PRNSIGMAP.
1. Various minor internal refactoring.

**Full Changelog**: https://github.com/semuconsulting/pyrtcm/compare/v1.0.15...v1.0.16