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/parse/syntax/keyword.c

@@ -0,0 +1,21 @@
+#include "../syntax.h"
+
+bool peek_keyword_expr(struct bshell_parse_ctx *ctx)
+{
+	return peek_unknown_keyword(ctx) != BSHELL_KW_NONE;
+}
+
+bool parse_keyword_expr(struct bshell_parse_ctx *ctx, struct bshell_ast_node **out)
+{
+	switch (peek_unknown_keyword(ctx)) {
+	case BSHELL_KW_NONE:
+		return false;
+	case BSHELL_KW_IF:
+		return parse_if(ctx, out);
+	case BSHELL_KW_FUNC:
+		return parse_func(ctx, out);
+	default:
+		ctx->p_status = BSHELL_ERR_BAD_SYNTAX;
+		return false;
+	}
+}