docs: add dataset ORM tutorial page and update navigation with GFM documentation

Add new Dataset ORM tutorial page covering CRUD operations, query operators, schema evolution, and JSON field handling. Update navigation.yaml to include the new tutorial in the tutorials section. Enhance markdown module documentation with GitHub Flavored Markdown support details including tables, task lists, and language identifier attributes for syntax highlighting. Update tutorial index page and pagination links to reflect the new tutorial order. Refactor dataset.wren module source to introduce Sql and QueryBuilder classes with soft-delete support and identifier validation.

test/regex/match_class.wren

@@ -0,0 +1,49 @@
+// retoor <retoor@molodetz.nl>
+
+import "regex" for Regex, Match
+
+var re = Regex.new("(\\w+)@(\\w+)")
+var m = re.match("email: user@domain here")
+
+System.print(m.text) // expect: user@domain
+System.print(m.start) // expect: 7
+System.print(m.end) // expect: 18
+System.print(m.toString) // expect: user@domain
+
+System.print(m.groups.count) // expect: 3
+System.print(m.groups[0]) // expect: user@domain
+System.print(m.groups[1]) // expect: user
+System.print(m.groups[2]) // expect: domain
+
+System.print(m.group(0)) // expect: user@domain
+System.print(m.group(1)) // expect: user
+System.print(m.group(2)) // expect: domain
+
+System.print(m[0]) // expect: user@domain
+System.print(m[1]) // expect: user
+System.print(m[2]) // expect: domain
+
+System.print(m.group(100) == null) // expect: true
+System.print(m.group(-1) == null) // expect: true
+System.print(m[-1] == null) // expect: true
+System.print(m[999] == null) // expect: true
+
+var re2 = Regex.new("test")
+var m2 = re2.match("a test string")
+System.print(m2.start) // expect: 2
+System.print(m2.end) // expect: 6
+System.print(m2.text) // expect: test
+
+var re3 = Regex.new("^start")
+var m3 = re3.match("start of string")
+System.print(m3.start) // expect: 0
+System.print(m3.end) // expect: 5
+
+var re4 = Regex.new("end$")
+var m4 = re4.match("the end")
+System.print(m4.start) // expect: 4
+System.print(m4.end) // expect: 7
+
+var re5 = Regex.new("notfound")
+var m5 = re5.match("some text")
+System.print(m5 == null) // expect: true