chore: switch to internal/log

[iwpnd]

As discussed I switched to the internal logger and changed current print statements to their respective log level to the best of my knowledge. Also as discussed I did not touch the math package. #831

[coveralls]

Pull Request Test Coverage Report for Build d9b676b62-PR-837

• 2 of 23 (8.7%) changed or added relevant lines in 6 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.01%) to 45.13%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
atlas/map.go	0	1	0.0%
provider/postgis/util.go	0	1	0.0%
server/handle_map_capabilities.go	0	2	0.0%
internal/log/log.go	0	3	0.0%
atlas/atlas.go	0	4	0.0%
provider/postgis/postgis.go	2	12	16.67%

Totals
Change from base Build e593b4f85:	-0.01%
Covered Lines:	5486
Relevant Lines:	12156

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💛 - Coveralls

[gdey]

LGTM

[ARolek]

LGTM! Let me get your other PR merged into v0.15.x and then you can rebase this branch onto it.

Thanks for the tackling this issue!