Update Rsconscript and add main.d

Rsconscript

@@ -1,21 +1,11 @@
 configure do
-  check_cxx_compiler
-  check_program "flex"
-  check_program "bison"
-  check_lib ":libfl.a"
-  check_lib "pthread"
-  check_lib "freeimage"
+  check_d_compiler
 end
 
 env do |env|
-  env["CCFLAGS"] += %w[-Wall -O2]
-  env["CPPPATH"] += glob("src/**")
+  env["DFLAGS"] += %w[-Werror -O2]
+  env["D_IMPORT_PATH"] += %w[src]
 
-  env.CFile("^/parser/lexer.cc", "src/parser/parser.ll")
-  env.CFile("^/parser/parser.cc", "src/parser/parser.yy")
-  env["CPPPATH"] += ["#{env.build_root}/parser"]
-
-  sources = glob("src/**/*.cc")
-  sources += ["^/parser/lexer.cc", "^/parser/parser.cc"]
+  sources = glob("src/**/*.d")
   env.Program("fart", sources)
 end