Separate compilation and linker phases (#376)

Separate between compilation and linker phases to allow deploy time
linking and back-porting era compiler changes to fix #91. Unlinked
contract binaries (caused by missing libraries or missing factory
dependencies in turn) are emitted as raw ELF object.

Few drive by fixes:
- #98
- A compiler panic on missing libraries definitions.
- Fixes some incosistent type forwarding in JSON output (empty string
vs. null object).
- Remove the unused fallback for size optimization setting.
- Remove the broken `--lvm-ir`  mode.
- CI workflow fixes.

---------

Signed-off-by: Cyrill Leutwiler <bigcyrill@hotmail.com>
Signed-off-by: xermicus <bigcyrill@hotmail.com>
Signed-off-by: xermicus <cyrill@parity.io>

crates/yul/src/lexer/token/mod.rs

@@ -1,11 +1,11 @@
 //! The token.
 
-pub mod lexeme;
-pub mod location;
-
 use self::lexeme::Lexeme;
 use self::location::Location;
 
+pub mod lexeme;
+pub mod location;
+
 /// The token.
 /// Contains a lexeme and its location.
 #[derive(Debug, Clone, PartialEq, Eq)]