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>

js/resolc/package.json

@@ -1,7 +1,7 @@
 {
   "name": "@parity/resolc",
   "license": "Apache-2.0",
-  "version": "0.3.0",
+  "version": "0.4.0",
   "author": "Parity <admin@parity.io> (https://parity.io)",
   "module": "index.ts",
   "types": "./dist/index.d.ts",