#i117960# Basic: Line Input doesn't work in single-line If

i92642 added the ability to use certain keywords as variable names (eg. name = 1, line = "hi"),
but also caused a regression where "Line Input" is broken in single-line If statements.
This patch fixes that by allowing Then and Else to also be the start-of-line tokens expected to
immediately preceed the "Line" token in order for that "Line" token to be recognized a keyword instead
of a variable name. Also added FVT spreadsheet tests for "Line" as both a variable name and as "Line Input".

Patch by: me

(cherry picked from commit f8a51d0f)

basic/source/comp/token.cxx

@@ -433,7 +433,8 @@ SbiToken SbiTokenizer::Next()
     }
 special:
     // #i92642
-    bool bStartOfLine = (eCurTok == NIL || eCurTok == REM || eCurTok == EOLN);
+    bool bStartOfLine = (eCurTok == NIL || eCurTok == REM || eCurTok == EOLN ||
+            eCurTok == THEN || eCurTok == ELSE); // single line If
     if( !bStartOfLine && (tp->t == NAME || tp->t == LINE) )
     {
         return eCurTok = SYMBOL;