Rename some of the more stupidly named files in the Unix back end.

Notably pterm.c, which was a sensible name right at the start but
became a misnomer as soon as I created Unix PuTTY.

[originally from svn r5053]

unix/uxpterm.c

@@ -0,0 +1,56 @@
+/*
+ * pterm main program.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "putty.h"
+
+const char *const appname = "pterm";
+const int use_event_log = 0;	       /* pterm doesn't need it */
+const int new_session = 0, saved_sessions = 0;   /* or these */
+
+Backend *select_backend(Config *cfg)
+{
+    return &pty_backend;
+}
+
+int cfgbox(Config *cfg)
+{
+    /*
+     * This is a no-op in pterm, except that we'll ensure the
+     * protocol is set to -1 to inhibit the useless Connection
+     * panel in the config box.
+     */
+    cfg->protocol = -1;
+    return 1;
+}
+
+void cleanup_exit(int code)
+{
+    exit(code);
+}
+
+int process_nonoption_arg(char *arg, Config *cfg)
+{
+    return 0;                          /* pterm doesn't have any. */
+}
+
+char *make_default_wintitle(char *hostname)
+{
+    return dupstr("pterm");
+}
+
+int main(int argc, char **argv)
+{
+    extern int pt_main(int argc, char **argv);
+    extern void pty_pre_init(void);    /* declared in pty.c */
+
+    cmdline_tooltype = TOOLTYPE_NONNETWORK;
+    default_protocol = -1;
+
+    pty_pre_init();
+
+    return pt_main(argc, argv);
+}