DOC: Improve figures references and caption

The figures were not referenced correctly. We activate
the numfig parameter so that figures can be references to
by their number. We also add captions to the figures.
25 jobs for !735 with doc_monteverdi in 72 minutes and 53 seconds (queued for 6 seconds)
detached
Status Job ID Name Coverage
  Precheck
passed #29915
fast-build

00:10:12

failed #29916
allowed to fail
legal-check

00:03:13

 
  Prepare
passed #29931
centos-xdk-prepare

00:04:14

passed #29919
macos
macos-xdk-prepare

00:00:47

passed #29917
ubuntu-xdk-prepare

00:01:20

passed #29920
windows10
windows-10-prepare

00:01:49

passed #29921
windows8
windows-8-prepare

00:01:44

failed #29918
centos-xdk-prepare

00:01:10

 
  Build
passed #29924
centos-xdk-build

00:31:20

passed #29922
debian-build

00:26:11

passed #29933
macos
macos-xdk-build

00:12:10

passed #29923
ubuntu-xdk-build-doc

00:37:05

passed #29928
ubuntu-xdk-qa-code-coverage

00:56:01

passed #29929
ubuntu-xdk-qa-static-analysis

00:38:52

passed #29926
windows10
windows-10-build

00:58:11

passed #29927
windows8
windows-8-build

00:30:05

failed #29925
macos
macos-xdk-build

00:09:12

 
  Report
passed #29930
ubuntu-xdk-report

00:05:15

 
  External
passed cdash:centos-6.6-gcc

passed cdash:debian-testing-gcc

passed cdash:macos-10.11.6-clang

passed cdash:ubuntu-18.04-llvm-qa

passed cdash:windows-10-x64-vc14.0

passed cdash:windows-8.1-x86-vc14.0

failed cdash:macos-10.11.6-clang

 
Name Stage Failure
failed
legal-check Precheck
$ ./CI/contributors_check.sh

WARNING: ***************************************************************
WARNING: Unknown contributors found:
WARNING: - Luc Hermitte <luc.hermitte@c-s.fr>
WARNING: Check if they have signed the contributor license agreements.
WARNING: ***************************************************************

ERROR: Job failed: exit code 1