Initial commit: Klammertext source distribution

Curated source subset assembled by klammertext-dev's doc/make_dist.sh: the Klammermachine (mac), the Standard Klammer Set (sks), the commands (com), editor plugins and install guides (doc), a test subset (tst), and lib/bin placeholders. Builds with 'make -C com'.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

mac/error.cpp

@@ -0,0 +1,35 @@
+#include "error.h"
+#include "show.h"
+#include "util.h"
+#include "file.h"
+
+bool display_source(const std::string& filename_arg)
+{
+    if (filename_arg.empty()) {
+        return false;
+    } else {
+        fs::path filename = fs::path(filename_arg).filename();
+        return sks_commands.count(filename) == 0;
+    }
+}
+
+void Error::print_message(const std::string& epilog)
+{
+    if (epilog != "")
+        //desc += "  " + epilog + "\n";
+        m_desc += epilog + "\n";
+    if (m_just)
+        m_desc = justify(m_desc, 80, 0);
+    std::cerr << "\n" << red << command_name << " (" << m_type << " error)";
+    if (display_source(m_loc.m_filename)) {
+        std::cerr << ":\n  " << m_loc.m_filename;
+    }
+    if (m_loc.m_line > -1) {
+        std::cerr << ", line " << m_loc.m_line;
+    }
+    if (m_loc.m_chr > -1) {
+        std::cerr << ", character " << m_loc.m_chr + 1;
+    }
+    std::cerr << ":\n\n" << m_desc << reset << "\n";
+    std::cout << reset;
+}