nimbus.nim: ban in-source builds

nimbus.1

@@ -31,6 +31,7 @@ file is located.
 .It Ar buildDir
 Build directory,
 location where all generated files should be placed.
+In-source builds are explicitly banned.
 .
 .It Fl Fl binDir : Ns Ar path
 Set the executable directory.

src/nimbus.nim

@@ -47,6 +47,9 @@ proc setup(options: Options) =
   echo "Source dir: " & options.getSourceDir()
   echo "Build dir: " & options.getBuildDir()
 
+  if options.getSourceDir() == options.getBuildDir():
+    quit("In-source builds are not allowed")
+
   let pkgInfo = initPackageInfo(options)
   echo "Project name: " & pkgInfo.name
   echo "Project version: " & pkgInfo.version