bshell: re-organise build into three separate components

bshell: the front-end binary
bshell.runtime: contains the parser, compiler, and classes needed to run bshell scripts
bshell.core: contains the builtin commandlets and aliases

bshell.runtime/ast/if-branch.c

@@ -0,0 +1,24 @@
+#include <bshell/ast.h>
+
+static enum bshell_status collect_children(
+	struct bshell_ast_node *node,
+	struct bshell_ast_iterator *it)
+{
+	struct bshell_if_branch_ast_node *if_branch
+		= (struct bshell_if_branch_ast_node *)node;
+	if (if_branch->n_cond) {
+		bshell_ast_iterator_enqueue(it, if_branch->n_cond);
+	}
+
+	if (if_branch->n_body) {
+		bshell_ast_iterator_enqueue(it, if_branch->n_body);
+	}
+
+	return BSHELL_SUCCESS;
+}
+
+struct bshell_ast_node_definition if_branch_bshell_ast_node = {
+	.def_id = BSHELL_AST_IF_BRANCH,
+	.def_node_size = sizeof(struct bshell_if_branch_ast_node),
+	.def_collect_children = collect_children,
+};