introduce TermHelper class
implement Terminal.editline
correct size handling in editline
add skeleton for NanoEditor
Merge branch 'develop' into feature/write_post

Conflicts:
	.rubocop_todo.yml
	termapp/processors/read_board_menu.rb
Merge branch 'develop' into feature/write_post

Conflicts:
	.rubocop_todo.yml
	termapp/terminal.rb
implement backspace in NanoEditor
implement up/down arrow key in NanoEditor
implement scrolling in up/down arrow key for NanoEditor
finish write feature
Merge branch 'feature/write_post' into develop

Conflicts:
	.rubocop_todo.yml
	termapp/application.rb
	termapp/terminal.rb