Convert .tgs with go libraries (and cgo) (telegram) (#1569)

This commit adds support for go/cgo tgs conversion when building with the -tags `cgo`
The default binaries are still "pure" go and uses the old way of converting.

* Move lottie_convert.py conversion code to its own file

* Add optional libtgsconverter

* Update vendor

* Apply suggestions from code review

* Update bridge/helper/libtgsconverter.go

Co-authored-by: Wim <wim@42.be>

vendor/github.com/Benau/go_rlottie/vector_vbrush.cpp

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2020 Samsung Electronics Co., Ltd. All rights reserved.
+
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "vector_vbrush.h"
+
+V_BEGIN_NAMESPACE
+
+VGradient::VGradient(VGradient::Type type)
+    : mType(type)
+{
+    if (mType == Type::Linear)
+        linear.x1 = linear.y1 = linear.x2 = linear.y2 = 0.0f;
+    else
+        radial.cx = radial.cy = radial.fx =
+        radial.fy = radial.cradius = radial.fradius = 0.0f;
+}
+
+void VGradient::setStops(const VGradientStops &stops)
+{
+    mStops = stops;
+}
+
+VBrush::VBrush(const VColor &color) : mType(VBrush::Type::Solid), mColor(color)
+{
+}
+
+VBrush::VBrush(uchar r, uchar g, uchar b, uchar a)
+    : mType(VBrush::Type::Solid), mColor(r, g, b, a)
+
+{
+}
+
+VBrush::VBrush(const VGradient *gradient)
+{
+    if (!gradient) return;
+
+    mGradient = gradient;
+
+    if (gradient->mType == VGradient::Type::Linear) {
+        mType = VBrush::Type::LinearGradient;
+    } else if (gradient->mType == VGradient::Type::Radial) {
+        mType = VBrush::Type::RadialGradient;
+    }
+}
+
+VBrush::VBrush(const VTexture *texture):mType(VBrush::Type::Texture), mTexture(texture)
+{
+}
+
+V_END_NAMESPACE