CLI: get rid of duplication in JVM/JS scripts

compiler/cli/bin/kotlinc.bat

@@ -1,17 +1,48 @@
 @echo off
+rem based on scalac.bat from the Scala distribution
+rem ##########################################################################
+rem # Copyright 2002-2011, LAMP/EPFL
+rem # Copyright 2011-2015, JetBrains
+rem #
+rem # This is free software; see the distribution for copying conditions.
+rem # There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
+rem # PARTICULAR PURPOSE.
+rem ##########################################################################
 
-rem Copyright 2010-2015 JetBrains s.r.o.
-rem
-rem Licensed under the Apache License, Version 2.0 (the "License");
-rem you may not use this file except in compliance with the License.
-rem You may obtain a copy of the License at
-rem
-rem http://www.apache.org/licenses/LICENSE-2.0
-rem
-rem Unless required by applicable law or agreed to in writing, software
-rem distributed under the License is distributed on an "AS IS" BASIS,
-rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-rem See the License for the specific language governing permissions and
-rem limitations under the License.
+rem We adopt the following conventions:
+rem - System/user environment variables start with a letter
+rem - Local batch variables start with an underscore ('_')
+
+@setlocal
+call :set_home
+
+if "%KOTLIN_COMPILER%"=="" set KOTLIN_COMPILER=org.jetbrains.kotlin.cli.jvm.K2JVMCompiler 
+
+if not "%JAVA_HOME%"=="" (
+  if exist "%JAVA_HOME%\bin\java.exe" set "_JAVACMD=%JAVA_HOME%\bin\java.exe"
+)
+
+if "%_JAVACMD%"=="" set _JAVACMD=java
+
+rem We use the value of the JAVA_OPTS environment variable if defined
+set _JAVA_OPTS=-Xmx256M -Xms32M -noverify
+
+"%_JAVACMD%" %_JAVA_OPTS% -cp "%_KOTLIN_HOME%\lib\kotlin-preloader.jar" ^
+  org.jetbrains.kotlin.preloading.Preloader "%_KOTLIN_HOME%\lib\kotlin-compiler.jar" ^
+  %KOTLIN_COMPILER% 4096 notime %*
+
+exit /b %ERRORLEVEL%
+goto end
+
+rem ##########################################################################
+rem # subroutines
+
+:set_home
+  set _BIN_DIR=
+  for %%i in (%~sf0) do set _BIN_DIR=%_BIN_DIR%%%~dpsi
+  set _KOTLIN_HOME=%_BIN_DIR%..
+goto :eof
+
+:end
+@endlocal
 
-call %~dps0kotlinc-jvm.bat %*