Fetch EOP from IERS via HTTP

[attipaci]

C99 API

Added

• novas_fetch_eop() -- to obtain cubic spline interpolated EOP from IERS for given Julian Date.
• novas_fetch_eop_unix() -- to obtain cubic spline interpolated EOP from IERS for a given UNIX time.
• novas_set_eop_url() / novas_get_eop_url() -- to use alternative (e.g. mirrored) URLs for IERS EOP series, or to check what URLs are currently configured.
• novas_cleanup_eop() -- to free up resources used for obtaining EOP data from IERS.
• novas_set_auto_fetch_eop() and novas_is_auto_fetch_eop() -- To control and check whether automatic fetching of EOP values from IERS is allowed if needed.
• novas_set_leap_list() -- to use a local leap-seconds.list data file (at least until it's expired).
• novas_leap_lookup() -- to look up leap seconds for a given UNIX time.

Changed

• novas_set_time() and related functions, and novas_make_frame() changed to fetch EOP values from IERS if the arguments for these are NAN and fetching is allowed.

C++11 API

Added

• EOP::fetch_for_jd(), EOP::fetch_for_mjd(), EOP::fetch_for(), and EOP::fetch_current() methods.

Changed

• Time constructors will fetch EOP as needed (if allowed) if dUT1 is undefined (NAN), and the EOP parameter is now optional as a result.
• EOP values to GeodeticObserver are now optional, and invalid EOP does not invalidate the observer so long as automatic fetching of EOP is allowed.
• Frame will fetch polar offsets from IERS if the geodetic observer does not provide these, and fetching is allowed.

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[codecov]

Codecov Report

❌ Patch coverage is 71.26437% with 100 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/c99/iers.c	78.19%	58 Missing ⚠️
src/cpp/EOP.cpp	6.06%	31 Missing ⚠️
src/cpp/Observer.cpp	73.07%	7 Missing ⚠️
src/cpp/Frame.cpp	71.42%	2 Missing ⚠️
src/c99/frames.c	83.33%	1 Missing ⚠️
src/c99/timescale.c	83.33%	1 Missing ⚠️

📢 Thoughts on this report? Let us know!

[coveralls]

Coverage Report for CI Build 25672560778

Coverage decreased (-1.3%) to 97.793%

Details

• Coverage decreased (-1.3%) from the base build.
• Patch coverage: 104 uncovered changes across 6 files (251 of 355 lines covered, 70.7%).
• No coverage regressions found.

Uncovered Changes

File	Changed	Covered	%
src/c99/iers.c	269	211	78.44%
src/cpp/EOP.cpp	37	2	5.41%
src/cpp/Observer.cpp	26	19	73.08%
src/cpp/Frame.cpp	7	5	71.43%
src/c99/frames.c	6	5	83.33%
src/c99/timescale.c	6	5	83.33%

Coverage Regressions

No coverage regressions found.

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Coverage Stats

Relevant Lines:	9698
Covered Lines:	9484
Line Coverage:	97.79%
Coverage Strength:	38619.12 hits per line

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💛 - Coveralls