Readme and early CI

This commit prepares the code to be uploaded to gitlab.
Included is a small readme and basic CI.

Signed-off-by: Ava Affine <ava@sunnypup.io>

.gitlab-ci.yml

@@ -0,0 +1,28 @@
+default:
+  image: rustlang/rust:nightly
+
+stages:
+  - build
+  - test
+
+compile-library:
+  stage: build
+  script:
+    - cargo build --lib
+
+compile-decomposer:
+  stage: build
+  script:
+    - cargo build --bin decomposer
+
+unit-test-language-frontend:
+  stage: test
+  script:
+    - cargo test lexer
+    - cargo test parser
+
+unit-test-number-package:
+  stage: test
+  script:
+    - cargo test number
+