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

lib/sql-js/make.sh

@@ -0,0 +1,9 @@
+#!/bin/bash -e
+
+docker build -t sqliteviz/sqljs .
+
+rm -r dist || true
+
+CONTAINER=$(docker create sqliteviz/sqljs)
+docker cp $CONTAINER:/tmp/build/dist .
+docker rm $CONTAINER