Code review comment for lp:~widelands-dev/widelands/empire-mission-3

I did a first round of proofreading on the texts.

Note that objective names are identifier code and should chosen to make this obvious - a-z and _ only. For example:

   obj_find_artifacts = {
      name = "Find the pieces of Neptune's shrine",

should be

   obj_find_artifacts = {
      name = "find_artifacts",

or

   obj_find_artifacts = {
      name = "find_neptunes_shrine",