v0.31.0

Most relevant commits:

• compiler/ast: remove Macro node and use Func instead
• compiler/checker: fix panic showing a Scriggo defined type value
• compiler/checker,templates: show values of Scriggo defined types
• templates: fix panic showing a []byte defined type value in CSS context
• runtime: move 'typeof' field to 'env' and add TypeOf method to Env
• all: replace TypeOf function with the Types interface
• runtime: fix Typify with Scriggo defined types using the Types interface
• compiler,templates: support Markdown as template language
• scriggo,scripts,templates: rename 'Load' methods to 'Build'
• compiler: rename 'Compile...' methods to 'Build...'
• templates: rename 'Render' method to 'Run'
• compiler/parser: parse HTML tags in Markdown context
• compiler/lexer: fix column of tokens when "\n\r" used as line ending
• compiler/lexer, templates: escape values in Markdown code blocks
• all: improve runtime support for templates