maint: Fix bug in transition filter

* dietncl/filter/transition.lua (filter.apply): Add anchors to gmatch
regexp.
maint: Break prenorm.lua into prenorm[1-5].lua

* dietncl/filter/prenorm1.lua: New filter; handles 1st prenorm step.
* dietncl/filter/prenorm2.lua: New filter; handles 2nd prenorm step.
* dietncl/filter/prenorm3.lua: New filter; handles 3rd prenorm step.
* dietncl/filter/prenorm4.lua: New filter; handles 4th prenorm step.
* dietncl/filter/prenorm5.lua: New filter; handles 5th prenorm step.
* tests/test-filter-prenorm1.lua: New test; checks prenorm1.
* tests/test-filter-prenorm2.lua: New test; checks prenorm2.
* tests/test-filter-prenorm3.lua: New test; checks prenorm3.
* tests/test-filter-prenorm4.lua: New test; checks prenorm4.
* tests/test-filter-prenorm5.lua: New test; checks prenorm5.
* Makefile (TESTS): Updated accordingly.
maint: Cleanup syntax and fix comments

* build-aux/sclua-copyright.pl: New script; check license text.
* build-aux/sclua.pl: New script; sanity checks for Lua files.
* Makefile (syntax-check): New target; run syntax checks.
* dietncl/filter/import.lua: Cleanup syntax and fix comments.
* dietncl/filter/prenorm1.lua: Likewise.
* dietncl/filter/prenorm2.lua: Likewise.
* dietncl/filter/prenorm3.lua: Likewise.
* dietncl/filter/prenorm4.lua: Likewise.
* dietncl/filter/prenorm5.lua: Likewise.
* dietncl/filter/region.lua: Likewise.
* dietncl/filter/transition.lua: Likewise.
* dietncl/init.lua: Likewise.
* dietncl/nclaux.lua: Likewise.
* dietncl/path.lua: Likewise.
* dietncl/xmlsugar.lua: Likewise.
* tests/test-filter-import.lua: Likewise.
* tests/test-filter-prenorm1.lua: Likewise.
* tests/test-filter-prenorm2.lua: Likewise.
* tests/test-filter-prenorm3.lua: Likewise.
* tests/test-filter-prenorm4.lua: Likewise.
* tests/test-filter-prenorm5.lua: Likewise.
* tests/test-filter-region.lua: Likewise.
* tests/test-filter-transition.lua: Likewise.
* tests/test-init-parse.lua: Likewise.
* tests/test-init-parsestring.lua: Likewise.
* tests/test-nclaux-gen-id.lua: Likewise.
* tests/test-nclaux-timetoseconds.lua: Likewise.
* tests/test-path-absolute.lua: Likewise.
* tests/test-path-join.lua: Likewise.
* tests/test-path-relative.lua: Likewise.
* tests/test-path-split.lua: Likewise.
* tests/test-xmlsugar-attributes.lua: Likewise.
* tests/test-xmlsugar-children.lua: Likewise.
* tests/test-xmlsugar-clone.lua: Likewise.
* tests/test-xmlsugar-equal.lua: Likewise.
* tests/test-xmlsugar-eval.lua: Likewise.
* tests/test-xmlsugar-gmatch.lua: Likewise.
* tests/test-xmlsugar-insert.lua: Likewise.
* tests/test-xmlsugar-match.lua: Likewise.
* tests/test-xmlsugar-remove.lua: Likewise.
* tests/test-xmlsugar-replace.lua: Likewise.
* tests/test-xmlsugar-userdata.lua: Likewise.
* tests/util.lua: Likewise.
Merge branch 'master' of https://github.com/gflima/dietncl

Conflicts:
	dietncl/filter/prenorm.lua
	tests/test-filter-prenorm.lua