Merge branch 'develop' into merge/JAL-3310_and_JAL-3300

diff --combined build.gradle
index 9aedd2f,f5149da..71eb491
--- 1/build.gradle
--- 2/build.gradle
+++ b/build.gradle
@@@ -97,19 -97,6 +97,19 @@@ if (JAVA_VERSION.equals("1.8")) 
      '--module-path', ext.modules_compileClasspath.asPath,
      '--add-modules', j11modules
    ]
 +} else if (JAVA_VERSION.equals("12") || JAVA_VERSION.equals("13")) {
 +  JAVA_INTEGER_VERSION = JAVA_VERSION
 +  libDir = j11libDir
 +  libDistDir = j11libDir
 +  compile_source_compatibility = JAVA_VERSION
 +  compile_target_compatibility = JAVA_VERSION
 +  getdown_alt_java_min_version = getdown_alt_java11_min_version
 +  getdown_alt_multi_java_location = getdown_alt_java11_txt_multi_java_location
 +  eclipse_java_runtime_name = "JavaSE-11"
 +  additional_compiler_args += [
 +    '--module-path', ext.modules_compileClasspath.asPath,
 +    '--add-modules', j11modules
 +  ]
  } else {
    throw new GradleException("JAVA_VERSION=$JAVA_VERSION not currently supported by Jalview")
  }
@@@ -484,13 -471,20 +484,20 @@@ task convertBuildingMD(type: Exec) 
    def buildingMD = "$jalviewDir/$docDir/building.md"
    def css = "$jalviewDir/$docDir/github.css"
  
-   def pandoc = pandoc_exec
+   def pandoc = null
+   pandoc_exec.split(",").each {
+     if (file(it.trim()).exists()) {
+       pandoc = it.trim()
+       return true
+     }
+   }
+ 
    def hostname = "hostname".execute().text.trim()
-   if (! file(pandoc).exists() && hostname.equals("jv-bamboo")) {
+   if ((pandoc == null || ! file(pandoc).exists()) && hostname.equals("jv-bamboo")) {
      pandoc = System.getProperty("user.home")+"/buildtools/pandoc/bin/pandoc"
    }
  
-   if (file(pandoc).exists()) {
+   if (pandoc != null && file(pandoc).exists()) {
      commandLine pandoc, '-s', '-o', buildingHTML, '--metadata', 'pagetitle="Building Jalview from Source"', '--toc', '-H', css, buildingMD
    } else {
      commandLine "true"