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/dds/README.md

@@ -10,12 +10,16 @@
 
 	make all
 
-	NOTE: This entry may not compile when using modern compilers.
 
 ### To run
 
 	./dds
 
+
+NOTE: this entry uses `gets()` so you might get a warning when compiling and
+running this entry.
+
+
 ## Judges' comments
 
     Give the following lines as input:
@@ -25,6 +29,11 @@
 
     Be sure not to run out of fuel!
 
+
+    Modern compilers could not compile this entry but Yusuke Endoh supplied a patch
+    which lets it compile. Thank you Yusuke!
+
+
 ## Author's comments
 
     This is the DDS-BASIC Interpreter (Version 1.00).