Fix #106: the current working directory should be always included in the include path

docs/lang/modules.md

@@ -11,7 +11,8 @@ Each module has a name, which is its unique identifier.
 A module name is a sequence of slash-separated valid Millfork identifiers.
 The name also defines where the module is located:
 a module named `a/b` is presumed to exist in `a/b.mfk`
-and it's looked up first in the current working directory,
+and it's looked up first in the directory that contains the current source file,
+then in the current working directory,
 and then in the include directories.
 
 A module can import other modules, using the `import` statement. 

src/main/scala/millfork/Main.scala

@@ -241,10 +241,10 @@ object Main {
           log.debug(s"Failed to find the default include path: $err")
         case Right(path) =>
           log.debug(s"Automatically detected include path: $path")
-          return c.copy(includePath = List(path) ++ c.extraIncludePath)
+          return c.copy(includePath = List(System.getProperty("user.dir"), path) ++ c.extraIncludePath)
       }
     }
-    c.copy(includePath = c.includePath ++ c.extraIncludePath)
+    c.copy(includePath = System.getProperty("user.dir") :: (c.includePath ++ c.extraIncludePath))
   }
 
   private def assembleForMos(c: Context, platform: Platform, options: CompilationOptions): AssemblerOutput = {