Revamped and documented the .gitignore file

.gitignore

@@ -1,31 +1,52 @@
+# This file is for excluding files from Git versioning which are *frequently*
+# encountered in a Melody development repository.  To have Git ignore less
+# frequently encountered files, please add them to this repository's
+# .git/info/exclude file or $HOME/.gitignore.
+#
+# Try "git help ignore" for more details...
+
+#####################################################
+##    Common backup, recovery and project files    ##
+#####################################################
+.DS_Store
+*#
+*~
+pod2htm*
+*.ORIG
+*.tmproj
+
+#####################################################
+##           Perltidy-generated files              ##
+#####################################################
+*.ERR
+*.LOG
+*.TEE
+*.tdy
+*.bak
+
+#####################################################
+##  Files generated by the build/test frameworks   ##
+#####################################################
 build-language-stamp
-# extlib/Data
-index.html
-# lib/MT.pm
 lib/MT/L10N/de-iso-8859-1.pm
 lib/MT/L10N/es-iso-8859-1.pm
 lib/MT/L10N/fr-iso-8859-1.pm
 lib/MT/L10N/nl-iso-8859-1.pm
-# mt-check.cgi
-*#
-mt-config.cgi
-mt-config.cgi-original
-mt-static/css/main.css
-mt-static/css/simple.css
-# mt-static/js/common
-mt-static/js/mt_core_compact.js
 mt-static/mt_de.js
 mt-static/mt_es.js
 mt-static/mt_fr.js
 mt-static/mt_ja.js
 mt-static/mt_nl.js
+mt-static/css/main.css
+mt-static/css/simple.css
+mt-static/js/mt_core_compact.js
+
+#####################################################
+##           Usage related files                   ##
+#####################################################
+mt-config.cgi
 mt-static/support/dashboard
 mt-static/support/logs
 mt-static/support/themes
 mt-static/support/assets_c
 mt-static/support/uploads
-# php/mt.php
-# readme.html
-*.tmproj
-.DS_Store
-ru-filter.pl