poppler: fix argument name

It is an action not an event.
poppler: revert conversion function name rules

rval2XXX ->
XXX_from_ruby_object

XXX2rval ->
ruby_object_from_XXX

Because XXX_from_YYY naming rules are used in Ruby/Poppler.
poppler: remove "event" word and use "action" instead

Because they are "action" not "event".
poppler: fix indent
poppler: fix a typo

rb_cPopplerActionRend tion ->
rb_cPopplerActionRendition
                     +
poppler: allign continuous line marks
poppler: fix indent
poppler: allign continuous line marks
poppler: use "URI" for URI notation

Because URI is the normal notation.