(Refiles to delete extraneous word in first paragraph) DOHA/RIYADH, March 19 (Reuters) - Leading nations in Europe, with Japan, said on Thursday they would act to stabilise energy markets and join "a... (Refiles to delete extraneous word in first paragraph) By Andrew Mills and Timour Azhari DOHA/RIYADH, March 19 (Reuters) - Leading nations in Europe, with Japan, said on Thursday they would act to stabilise energy markets and join "appropriate effort... [6098 chars]