LIMA — Two decades after the capture of its messianic leader precipitated the Shining Path’s rapid military decline, supporters of the Maoist insurgents who once bathed Peru in blood are attempting a comeback. Pushing the group’s fundamentalist agenda and calling for the release of those convicted of terrorism, the Movement for Amnesty and Fundamental Rights is winning adherents among a new generation with no memories of the horrors of the 1980s and early 1990s.