All 1990 entries now compile!

My first 41st, 51st and 29th (all depending on the base) birthday
updates (possibly more will follow but this is not a certainty). All the
1990 entries now compile!

In one we used a patch from Yusuke Endoh (thank you Yusuke!) which we
credited him in the README and in another we used a tip from him (use
-ansi at the compiler line) to get the other to compile (again, thank
you Yusuke!). We fixed the others. In the case of 1990/tbr/tbr.c the
author had supplied a shorter version and we fixed that one too.

Added 1990/.gitignore which has the built files of 1990 so that after
doing `cd 1990 ; make all' running `git status .' will not show any
untracked files.

1990/scjones/README.md

@@ -10,7 +10,18 @@
 
         make all
 
-	NOTE: This entry may not compile when using modern compilers.
+
+    Modern compilers might fail to compile this entry:
+
+	    scjones.c:1:7: error: expected ';' after top level declarator
+	    char*a??(??)=??<
+		  ^
+		  ;
+
+
+    but we were able to get it to compile with modern compilers by specifying the
+    `-ansi` flag with a tip from Yusuke Endoh. Thank you Yusuke!
+
 
 ### To run