Add support for P2A outputs

In order to support v3 commitments in lightning, we need to use P2A
(pay-to-anchor) outputs, which are currently rejected by our script
interpreter.

See ACINQ/bitcoin-kmp#164

Author: t-bast

pom.xml

@@ -3,7 +3,7 @@
     <groupId>fr.acinq</groupId>
     <artifactId>bitcoin-lib_2.13</artifactId>
     <packaging>jar</packaging>
-    <version>0.44</version>
+    <version>0.45</version>
     <description>Simple Scala Bitcoin library</description>
     <url>https://github.com/ACINQ/bitcoin-lib</url>
     <name>bitcoin-lib</name>
@@ -153,12 +153,12 @@
         <dependency>
             <groupId>fr.acinq.bitcoin</groupId>
             <artifactId>bitcoin-kmp-jvm</artifactId>
-            <version>0.27.0</version>
+            <version>0.28.0</version>
         </dependency>
         <dependency>
             <groupId>fr.acinq.secp256k1</groupId>
             <artifactId>secp256k1-kmp-jni-jvm</artifactId>
-            <version>0.20.0</version>
+            <version>0.21.0</version>
         </dependency>
         <dependency>
             <groupId>org.scodec</groupId>

src/main/scala/fr/acinq/bitcoin/scalacompat/Script.scala

@@ -190,4 +190,10 @@ object Script {
    */
   def witnessScriptPathPay2tr(internalKey: XonlyPublicKey, script: ScriptTree.Leaf, witness: ScriptWitness, scriptTree: ScriptTree): ScriptWitness = bitcoin.Script.witnessScriptPathPay2tr(internalKey.pub, scala2kmp(script), witness, scala2kmp(scriptTree))
 
+  /** Standard P2A (pay-to-anchor) output. */
+  val pay2anchor: Seq[ScriptElt] = bitcoin.Script.getPay2anchor.asScala.map(kmp2scala).toList
+
+  /** An empty witness script must be used to spend [[pay2anchor]] outputs. */
+  val witnessPay2anchor: ScriptWitness = bitcoin.Script.getWitnessPay2anchor
+
 }