* fixes for Go 1.13 + retain go module 1.12 GOPATH behavior for internal/examples
* update docker images to 5.13.0
* new docker images (windows_64_shared_512, linux_512, darwin_512)
* update examples to match the Qt 5.13 api
* bump android minSdkVersion to 21 (5.0 / lollipop)
* bump OpenSSL version for android docker deployments to 1.1.1a
* let the binding use the 513 env by default
you can use QT_VERSION=5.12.0 and/or QT_API=5.12.0 to keep the binding backward compatible with your code
just setting QT_API=5.12.0 alone should also be sufficient to keep docker deployments working
if you did install an official Qt version then just set the correct QT_VERSION and procede as usual
* make private constructors work across packages
* fix go module related docker deployment issues
* make svg module optional
* bump openssl version for android docker images
* new (experimental) function to directly call qml functions from go
* fix QVariant related issue with older Qt versions
* fix qtmoc issue
* qml support for map[string]T, map[string]map[string]*QVariant, [][]*QVariant, []map[string]*QVariant and map[string][]*QVariant
* qml support for []*CustomMocStruct
* new "NewQVariant1(interface{}) *QVariant" and "(*QVariant).ToInterface() interface{}" functions
* fix docker go module support
* js/wasm GOCACHE fix for Go 1.12+
* make use of the official Go 1.12 wasm build and replace js.NewCallback with js.FuncOf
* update docker images to Go 1.12.4
* revive raspberry images
* fix raspberry related bundling issue
* add the multimedia module to the raspberry images
* fix raspberry related QT_API issue
* remove unecessary *char to []byte copy overhead in some unlikely cases
* fix Qt install script
* initial partially support for Felgo (former V-Play) on darwin
* fix charts/audio example and darwin
* fix common/widgets_demo example on iOS (issue #451)
* fix widgets/renderer memory leak
* fix possible QT_PKG_CONFIG + QT_VERSION race condition
* fix static linux docker image
