Exporting database resets pragmas to their default values

As of commit 1ee5a18, which fixes issues #9 and #55, the export() function closes the SQLite database (sqlite3_close_v2()) and reopens it (sqlite3_open()). This silently causes any pragmas that have been set since the database was last opened to be reset to their default values. This can have some nasty side-effects - the most obvious (and perhaps most damaging) example of this is with the foreign_keys pragma, which tells SQLite to enforce foreign key constraints on insertions and updates and is OFF by default.

Here's a MWE demonstrating the problem:

var sql = require("./sql.js");
var util = require("util");

var db = new sql.Database();
db.run("pragma foreign_keys = on");
db.run("create table x (xa int, xb char, primary key (xa)) without rowid");
db.run("create table y (ya int, yb int not null references x(xa), primary key (ya)) without rowid");

//db.export();

db.run("insert into x values (1, 'a'), (2, 'b'), (3, 'c')");

db.run("insert into y values (1, 1)");
db.run("insert into y values (999, 999)");

console.log(util.inspect(db.exec("select * from x order by xa"), false, null));
console.log(util.inspect(db.exec("select * from y order by ya"), false, null));

Output:

Error: FOREIGN KEY constraint failed
    at Error (<anonymous>)
    ...

With line 9 uncommented:

[ { columns: [ 'xa', 'xb' ],
    values: [ [ 1, 'a' ], [ 2, 'b' ], [ 3, 'c' ] ] } ]
[ { columns: [ 'ya', 'yb' ], values: [ [ 1, 1 ], [ 999, 999 ] ] } ]

I understand the need for the database to be closed and reopened, but is there any way the non-default pragma values that were set since the database was opened can be restored after it is reopened in the call to export()?

Start at the export() entry point and inspect the sqlite3_close_v2() and sqlite3_open() sequence described in the issue. Reproduce the provided foreign_keys example, then verify that exporting no longer resets pragma values such as foreign_keys after the database is reopened.