Pre-built custom sql.js for sqliteviz (#62)

* Proof-of-concept pre-built custom sql.js

* Rewrite Makefile as a couple of comprehensible Python scripts

* Add link to a blog post about transitive closure in SQLite

* Remove eval extension -- no much point as it only returns a string

* Consistently use existing Path objects

* Add basic tests scalar functions from extension-functions.c

* Test presence of functions from the rest of built extensions

* Use the same sqlite.com domain

* Add a couple SQLite compile flags that may make it a bit faster

* Add regexpi function test

* Add node about regexpi and REGEXP operator

* Workaround first build failure, rebuild lock file and minor fixes

package.json

@@ -19,7 +19,6 @@
     "react": "^16.13.1",
     "react-chart-editor": "^0.45.0",
     "react-dom": "^16.13.1",
-    "sql.js": "^1.5.0",
     "sqlite-parser": "^1.0.1",
     "vue": "^2.6.11",
     "vue-codemirror": "^4.0.6",
@@ -27,7 +26,8 @@
     "vue-router": "^3.2.0",
     "vuejs-paginate": "^2.1.0",
     "vuera": "^0.2.7",
-    "vuex": "^3.4.0"
+    "vuex": "^3.4.0",
+    "sql.js": "file:./lib/sql-js"
   },
   "devDependencies": {
     "@vue/cli-plugin-babel": "^4.4.0",