Ip tree reusability refactor - ASN stage II.

[zkauker]

Refactored version of loading IP-range based annotators. Fully unit-tested.

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This change is 

[coveralls]

Pull Request Test Coverage Report for Build 2073

• 550 of 777 (70.79%) changed or added relevant lines in 12 files are covered.
• 38 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+4.08%) to 57.33%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
asn/asn-annotator.go	34	38	89.47%
loader/loader.go	0	4	0.0%
manager/manager.go	42	48	87.5%
loader/csv-reader.go	25	34	73.53%
asn/asn-loader.go	80	92	86.96%
iputils/iputils.go	158	170	92.94%
geoloader/geoloader.go	6	23	26.09%
geolite2v2/geo-ip-ip-loader.go	82	101	81.19%
geolite2v2/geo-ip-loc-loader.go	50	79	63.29%
geoloader/geoloader-asn.go	0	43	0.0%
<!--	Total:	550	777	70.79%	-->

Files with Coverage Reduction	New Missed Lines	%
geolite2/geo-g2.go	7	43.78%
geolite2/geo-ip.go	31	31.69%
<!--	Total:	38		-->

Totals
Change from base Build 1995:	4.08%
Covered Lines:	1271
Relevant Lines:	2217

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💛 - Coveralls

[zkauker]

Reviewable status: 0 of 1 LGTMs obtained

_geolite2v2/geo-ip.go, line 1 at r6 (raw file):_

package geolite2v2

Is this intended to replace, or be used alongside, the geolite2/* code?

Yes, exactly. I didn't want to replace the code in-place to be able to use the old implementation as benchmark.

[gfr10598]

FYI, it appears that key parts of this were in fact implemented and merged in other PRs, for example PR #232 on April 15.