Add SQLite support, fix un-thread-safe DB caches, small performance f… (#172)

* Add SQLite support, fix un-thread-safe DB caches, small performance fixes

Signed-off-by: kim (grufwub) <grufwub@gmail.com>

* add SQLite licenses to README

Signed-off-by: kim (grufwub) <grufwub@gmail.com>

* appease the linter, and fix my dumbass-ery

Signed-off-by: kim (grufwub) <grufwub@gmail.com>

* make requested changes

Signed-off-by: kim (grufwub) <grufwub@gmail.com>

* add back comment

Signed-off-by: kim (grufwub) <grufwub@gmail.com>

vendor/modernc.org/memory/mmap_windows.go

@@ -0,0 +1,49 @@
+// Copyright 2017 The Memory Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package memory // import "modernc.org/memory"
+
+import (
+	"os"
+	"syscall"
+)
+
+const (
+	_MEM_COMMIT   = 0x1000
+	_MEM_RESERVE  = 0x2000
+	_MEM_DECOMMIT = 0x4000
+	_MEM_RELEASE  = 0x8000
+
+	_PAGE_READWRITE = 0x0004
+	_PAGE_NOACCESS  = 0x0001
+)
+
+const pageSizeLog = 16
+
+var (
+	modkernel32      = syscall.NewLazyDLL("kernel32.dll")
+	osPageMask       = osPageSize - 1
+	osPageSize       = os.Getpagesize()
+	procVirtualAlloc = modkernel32.NewProc("VirtualAlloc")
+	procVirtualFree  = modkernel32.NewProc("VirtualFree")
+)
+
+// pageSize aligned.
+func mmap(size int) (uintptr, int, error) {
+	size = roundup(size, pageSize)
+	addr, _, err := procVirtualAlloc.Call(0, uintptr(size), _MEM_COMMIT|_MEM_RESERVE, _PAGE_READWRITE)
+	if err.(syscall.Errno) != 0 || addr == 0 {
+		return addr, size, err
+	}
+	return addr, size, nil
+}
+
+func unmap(addr uintptr, size int) error {
+	r, _, err := procVirtualFree.Call(addr, 0, _MEM_RELEASE)
+	if r == 0 {
+		return err
+	}
+
+	return nil
+}