Add the bool type. Few boolean-related bugfixes.

docs/abi/generated-labels.md

@@ -14,6 +14,8 @@ where `11111` is a sequential number and `xx` is the type:
 
 * `bc` – array bounds checking (`-fbounds-checking`)
 
+* `bo` – boolean type conversions
+
 * `c8` – constant `#8` for `BIT` when immediate addressing is not available
 
 * `co` – greater-than comparison

docs/lang/types.md

@@ -79,6 +79,8 @@ Its actual value is defined using the feature `NULLPTR`, by default it's 0.
 
 TODO
 
+* `bool` – a 1-byte boolean value
+
 ## Special types
 
 * `void` – a unit type containing no information, can be only used as a return type for a function.