ext_easy impl + demo + fixes

example/HConfig

@@ -0,0 +1,46 @@
+grbc_want_version("1.0")
+grbc_ext("GRBC_EXT_profiles")
+
+local test_lib = grbc_library(LibraryConfig.new({
+    name = "libtest",
+    files = {
+        grbc_file("test.c")
+    },
+    requirements = {},
+    include_dirs = {
+        grbc_file("include")
+    },
+    lib_type = LibraryType.Shared,
+    compile_flags = {},
+    linker_flags = {},
+    package_config = PackageConfig.new({
+        name = "libtest",
+        libraries = {},
+        include_dirs = {
+            grbc_file("include")
+        },
+        compile_flags = {},
+        linker_flags = {}
+    })
+}))
+
+local hello_world = grbc_executable(ExecutableConfig.new({
+    name = "hello_world",
+    files = {
+        grbc_file("main.c")
+    },
+    requirements = {
+        grbc_pkg("libtest")
+    },
+    include_dirs = {},
+    compile_flags = {},
+    linker_flags = {}
+}))
+
+grbc_task(TaskConfig.new({
+    name = "Clean",
+    task_id = "clean",
+    shell_script = "ninja -t clean"
+}))
+
+grbc_build("ninja")