v. 2.1

• Nest namespace rang (issue #167)
• Add ascii value 8 for backspace (issue #124)
• Add check for CMAKE_SKIP_INSTALL_RULES (issue #160)
• Add enter action (issue #177 - PR #180)
• Fix missing echo after paste of command (issue #185)
• Fix asio::io_context::work has no member named reset in old asio lib (issue #188)
• Shown in the complete and pluginmanager examples that the issue #96 was already fixed (issue #96)
• Allow custom prompt for menu (issue #101)