Support mariadb dumps with newlines

[josacar]

Closes #19

Changes:

• Read full statements instead of lines to support new MariaDB dumps
• Deleted single-use moduels
• Use abstract class to define engines
• Get rid of parse_copy_statement lambda and use macro to detect proper type when dispatching method calls

  
  In spec/triki_spec.cr:120:18

120 | scaffolder.scaffold(dump, output) ^ Error: instantiating 'Triki#scaffold(IO::Memory, IO::Memory)'

In src/triki.cr:83:21

83 | database_helper.generate_config(self, config, input_io, output_io) ^ Error: instantiating 'Triki::Base+#generate_config(Triki, Hash(String, Hash(String, Hash(Symbol, Array(Regex) | Array(String) | Bool | Int32 | Proc(Hash(String, Int32 | String | Nil), (Int32 | String | Nil)) | Proc(Hash(String, Int32 | String | Nil), Bool) | Proc(String) | Range(Int32, Int32) | String | Symbol) | Symbol) | Symbol), IO::Memory, IO::Memory)'

In src/triki/config_scaffold_generator.cr:9:24

9 | table_data = parse_copy_statement(line) ^ Error: undefined method 'parse_copy_statement' for Triki::SqlServer