Change constant key

src/calc.rs

@@ -191,7 +191,7 @@ impl Calculator {
                     self.state = CalculatorState::WaitingForRegister(RegisterState::Save);
                     Ok(())
                 }
-                '\t' => {
+                '`' => {
                     self.state = CalculatorState::WaitingForConstant;
                     Ok(())
                 }

src/main.rs

@@ -195,7 +195,7 @@ fn main() -> Result<(), Box<dyn Error>> {
                                 <ret>   => Dup             l      => Log\n\
                                 L       => Ln              e      => *10^\n\
                                 <right> => Swap            <down> => Edit\n\
-                                uU      => Undo/Redo       <tab>  => Constants\n\
+                                uU      => Undo/Redo       `      => Constants\n\
                                 m       => Macros          rR     => Registers\n\
                                 ^s      => Save Config     ^l     => Load Config\n\
                                 @       => Settings\