refactor: organised .gitignore, added .idea to ignore (#827)

.gitignore

@@ -1,18 +1,30 @@
-test
-build
-config.json
+# IDEs
+.vs
+.idea
+
+# doxygen generated files
 docs
-testdata/maxpower.pcm
-testdata/onandon.pcm
-buildtools/composer.phar
 docs/doxygen_sqlite3.db
+
+# build files
+build
+buildtools/composer.phar
 src/build
-.vs
+
+# tests
+test
+testdata/maxpower.pcm
+testdata/onandon.pcm
+
+# general folders
+/main
+tags
+core
 *.autosave
+.cache
+
+# general files
+config.json
 .misspell-fixer.ignore
-core
 compile_commands.json
-tags
-.cache
-src/dpp/dpp.rc
-/main
+src/dpp/dpp.rc