Git commits in Moodle 3.9.0 by David Monllaó

commit 6429236fcf7c372d64c33f1736a6d3892e7ee14b
Author: David Monllaó <davidm@moodle.com>
Date:   Mon, 06 Jan 2020 13:41:17 +0800
Tag:    v3.9.0-beta

MDL-67040 mlbackend_python: Adapt python ML to small datasets

commit e45b42cb3f2284fab6e99c5755f7ad9976a3e44a
Author: David Monllaó <davidm@moodle.com>
Date:   Mon, 06 Jan 2020 12:54:37 +0800
Tag:    v3.9.0-beta

MDL-67622 mlbackend_python: Fix f1score calculation

commit b1a6b2def25c2b77ab467ace6aaf664606b28dad
Author: David Monllaó <davidm@moodle.com>
Date:   Tue, 26 Nov 2019 14:39:14 +0800
Tag:    v3.9.0-beta

MDL-67304 analytics: Add missing png svg incorrect icon

commit e477e1350a2d38c254023562547fba24702ddb5f
Author: David Monllaó <davidm@moodle.com>
Date:   Tue, 12 Nov 2019 08:28:14 +0800
Tag:    v3.9.0-beta

MDL-67217 unittest: usleep and windows don't get along well