Upgrade Lets-Plot to 1.5.1-SNAPSHOT (#93)

* Update Lets-Plot to 1.5.1-SNAPSHOT.
* Add 'image export'.

Author: alshan

libraries/lets-plot.json

@@ -1,23 +1,28 @@
 {
   "properties": {
-    "api": "0.0.23-SNAPSHOT",
-    "js": "1.4.2",
+    "api": "0.0.26-SNAPSHOT",
+    "lib": "1.5.1-SNAPSHOT",
+    "js": "1.5.0",
     "isolatedFrame": ""
   },
   "link": "https://github.com/JetBrains/lets-plot-kotlin",
   "repositories": [
     "https://jetbrains.bintray.com/lets-plot-maven"
   ],
   "dependencies": [
-    "org.jetbrains.lets-plot:lets-plot-kotlin-api:$api"
+    "org.jetbrains.lets-plot:lets-plot-kotlin-api-kernel:$api",
+    "org.jetbrains.lets-plot:lets-plot-common:$lib",
+    "org.jetbrains.lets-plot:lets-plot-image-export:$lib"
   ],
   "imports": [
     "jetbrains.letsPlot.*",
     "jetbrains.letsPlot.geom.*",
     "jetbrains.letsPlot.stat.*",
     "jetbrains.letsPlot.label.*",
     "jetbrains.letsPlot.scale.*",
-    "jetbrains.letsPlot.facet.*"
+    "jetbrains.letsPlot.facet.*",
+    "jetbrains.letsPlot.sampling.*",
+    "jetbrains.letsPlot.export.*"
   ],
   "init": [
     "import jetbrains.letsPlot.LetsPlot",