signals: Fix *_generate_* signals -> *_generator_*
signals: Fix *_generate_* signals -> *_generator_*

For example, article_generate_preread is now article_generator_preread
for consistency with the other preread and context signals.

Rogdham/pelican,lazycoder-ru/pelican,lucasplus/pelican,HyperGroups/pelican,crmackay/pelican,Rogdham/pelican,lazycoder-ru/pelican,deanishe/pelican,zackw/pelican,rbarraud/pelican,talha131/pelican,iurisilvio/pelican,koobs/pelican,karlcow/pelican,number5/pelican,Scheirle/pelican,janaurka/git-debug-presentiation,TC01/pelican,koobs/pelican,Summonee/pelican,sunzhongwei/pelican,treyhunner/pelican,fbs/pelican,iurisilvio/pelican,simonjj/pelican,ehashman/pelican,kernc/pelican,ehashman/pelican,catdog2/pelican,arty-name/pelican,alexras/pelican,HyperGroups/pelican,sunzhongwei/pelican,joetboole/pelican,kernc/pelican,gymglish/pelican,deanishe/pelican,jo-tham/pelican,jo-tham/pelican,UdeskDeveloper/pelican,crmackay/pelican,sunzhongwei/pelican,rbarraud/pelican,Summonee/pelican,Rogdham/pelican,douglaskastle/pelican,11craft/pelican,florianjacob/pelican,jimperio/pelican,joetboole/pelican,ingwinlu/pelican,iKevinY/pelican,treyhunner/pelican,goerz/pelican,liyonghelpme/myBlog,kennethlyn/pelican,gymglish/pelican,btnpushnmunky/pelican,kernc/pelican,treyhunner/pelican,zackw/pelican,number5/pelican,Polyconseil/pelican,joetboole/pelican,avaris/pelican,abrahamvarricatt/pelican,koobs/pelican,jvehent/pelican,alexras/pelican,catdog2/pelican,karlcow/pelican,simonjj/pelican,janaurka/git-debug-presentiation,eevee/pelican,justinmayer/pelican,levanhien8/pelican,goerz/pelican,JeremyMorgan/pelican,catdog2/pelican,deved69/pelican-1,UdeskDeveloper/pelican,farseerfc/pelican,Summonee/pelican,florianjacob/pelican,janaurka/git-debug-presentiation,GiovanniMoretti/pelican,JeremyMorgan/pelican,simonjj/pelican,jimperio/pelican,iurisilvio/pelican,UdeskDeveloper/pelican,Scheirle/pelican,crmackay/pelican,liyonghelpme/myBlog,deved69/pelican-1,jimperio/pelican,btnpushnmunky/pelican,51itclub/pelican,ingwinlu/pelican,JeremyMorgan/pelican,zackw/pelican,abrahamvarricatt/pelican,getpelican/pelican,goerz/pelican,levanhien8/pelican,rbarraud/pelican,avaris/pelican,jvehent/pelican,GiovanniMoretti/pelican,Scheirle/pelican,florianjacob/pelican,eevee/pelican,deved69/pelican-1,ls2uper/pelican,garbas/pelican,ehashman/pelican,iKevinY/pelican,GiovanniMoretti/pelican,number5/pelican,abrahamvarricatt/pelican,garbas/pelican,ls2uper/pelican,11craft/pelican,btnpushnmunky/pelican,0xMF/pelican,talha131/pelican,sunzhongwei/pelican,lucasplus/pelican,TC01/pelican,lazycoder-ru/pelican,kennethlyn/pelican,getpelican/pelican,douglaskastle/pelican,lucasplus/pelican,liyonghelpme/myBlog,Polyconseil/pelican,levanhien8/pelican,TC01/pelican,ls2uper/pelican,ionelmc/pelican,farseerfc/pelican,gymglish/pelican,11craft/pelican,HyperGroups/pelican,jvehent/pelican,deanishe/pelican,liyonghelpme/myBlog,eevee/pelican,karlcow/pelican,kennethlyn/pelican,alexras/pelican,51itclub/pelican,51itclub/pelican,liyonghelpme/myBlog,garbas/pelican,douglaskastle/pelican