SD: Add Linear Lag and Route propagation model

Processed by Enola Henrotin.

See the forked project on https://gitlab.irstea.fr/david.dorchies/airgr

added ENHANCEMENT label

assigned to @david.dorchies

mentioned in commit david.dorchies/airgr@a45508d7

mentioned in commit david.dorchies/airgr@bb03e2fb

mentioned in commit david.dorchies/airgr@b7230c94

mentioned in commit david.dorchies/airgr@1b9865fa

mentioned in commit david.dorchies/airgr@b1644c21

mentioned in commit david.dorchies/airgr@057d235c

mentioned in commit david.dorchies/airgr@60d9bf61

mentioned in commit david.dorchies/airgr@3a1d358d

mentioned in commit david.dorchies/airgr@f8a06071

mentioned in commit david.dorchies/airgr@68225767

mentioned in commit david.dorchies/airgr@95c60ddc

mentioned in commit david.dorchies/airgr@6e4e1a1a

mentioned in commit david.dorchies/airgr@898a459a

mentioned in commit david.dorchies/airgr@5da5ccf0

mentioned in commit david.dorchies/airgr@9eab0a15

mentioned in commit david.dorchies/airgr@456d4eb5

mentioned in commit david.dorchies/airgr@31f8e94e

changed milestone to %v2.0