Because legionary is English, legionnaire is French, legionarius is Latin.
This patch renames the following files:
* art/actors/props/shields/rome_scutum_legionnaire.xml → rome_scutum_legionary.xml
* art/actors/units/romans/infantry_swordsman_c2.xml → infantry_swordsman_c_2.xml (see carthaginians)
* art/actors/units/romans/infantry_swordsman_c3.xml → infantry_swordsman_c_3.xml (ibidem)
* art/actors/units/romans/infantry_swordsman_c4.xml → infantry_swordsman_c_4.xml (ibidem)
* simulation/templates/units/rome_centurio_imperial.xml → rome_infantry_swordsman_c_4.xml (to match actor)
* simulation/templates/units/rome_legionnaire_imperial.xml → rome_infantry_swordsman_c_3.xml (idem)
* simulation/templates/units/rome_legionnaire_marian.xml → rome_infantry_swordsman_c_2.xml (idem)
Not done here is correcting the following scenarios and skirmishes, because uploading map files tends to go wrong on phabricator, because of their file names (D1042) and size (D989):
maps/scenarios/Cinema_Demo.xml
maps/scenarios/Miletus.xml
maps/scenarios/road demo.xml
maps/scenarios/Sandbox - Britons.xml
maps/scenarios/Sandbox - Carthaginians.xml
maps/scenarios/Sandbox - Gauls.xml
maps/scenarios/Sandbox - Romans.xml
maps/scenarios/Tropical Island.xml
maps/scenarios/We are Legion.xml
maps/skirmishes/Egypt (3v3).xml