Migrate to MPP build with Gradle

.gitignore

@@ -1,10 +1,13 @@
 .idea
 *.iml
 target
+build
+.gradle
 *~
 *.versionsBackup
 **/karma/node_modules
 **/karma/node
 **/karma/etc
 
 js/src/test/karma/package-lock.json
+

README.md

@@ -1,5 +1,8 @@
 [![Official JetBrains Project](https://jb.gg/badges/official.svg)](https://confluence.jetbrains.com/display/ALL/JetBrains+on+GitHub)
-[![Download](https://api.bintray.com/packages/kotlin/kotlinx.html/kotlinx.html/images/download.svg)](https://bintray.com/kotlin/kotlinx.html/kotlinx.html/_latestVersion)  [![npm](https://img.shields.io/npm/v/kotlinx-html.svg)](https://www.npmjs.com/package/kotlinx-html) [![TeamCity (simple build status)](https://img.shields.io/teamcity/http/teamcity.jetbrains.com/s/KotlinTools_KotlinxHtml_Build.svg)](https://teamcity.jetbrains.com/viewType.html?buildTypeId=KotlinTools_KotlinxHtml_Build&branch_Kotlin_KotlinX=%3Cdefault%3E&tab=buildTypeStatusDiv&guest=1) [ ![Kotlin](https://img.shields.io/badge/Kotlin-1.2.71-orange.svg) ](https://kotlinlang.org/) [![GitHub license](https://img.shields.io/badge/license-Apache%20License%202.0-green.svg?style=flat)](https://www.apache.org/licenses/LICENSE-2.0)
+[![GitHub license](https://img.shields.io/badge/license-Apache%20License%202.0-green.svg?style=flat)](https://www.apache.org/licenses/LICENSE-2.0)
+[![Kotlin](https://img.shields.io/badge/Kotlin-1.2.71-orange.svg) ](https://kotlinlang.org/)[![Download](https://api.bintray.com/packages/kotlin/kotlinx.html/kotlinx.html/images/download.svg)](https://bintray.com/kotlin/kotlinx.html/kotlinx.html/_latestVersion)
+[![npm](https://img.shields.io/npm/v/kotlinx-html.svg)](https://www.npmjs.com/package/kotlinx-html)
+[![TeamCity (simple build status)](https://teamcity.jetbrains.com/app/rest/builds/aggregated/strob:\(branch:\(buildType:\(id:KotlinTools_KotlinxHtml_BuildGradleMasterBranch\),policy:active_history_and_active_vcs_branches\),locator:\(buildType:\(id:KotlinTools_KotlinxHtml_BuildGradleMasterBranch\)\)\)/statusIcon.svg)](https://teamcity.jetbrains.com/viewType.html?buildTypeId=KotlinTools_KotlinxHtml_BuildGradleMasterBranch&branch_Kotlin_KotlinX=%3Cdefault%3E&tab=buildTypeStatusDiv&guest=1)
 
 # kotlinx.html