idiom.c: Fix an array-bounds compilation warning
idiom.c: Fix an array-bounds compilation warning

Rewrite increment_current_name().

Using gcc version 5.1.1:
idiom.c:197:15: warning: array subscript is below array bounds [-Warray-bounds]
   current_name[i]++;
               ^
idiom.c:197:15: warning: array subscript is below array bounds [-Warray-bounds]
idiom.c:199:16: warning: array subscript is below array bounds [-Warray-bounds]
    current_name[i] = 'A';

opencog/link-grammar,ampli/link-grammar,MadBomber/link-grammar,linas/link-grammar,ampli/link-grammar,ampli/link-grammar,opencog/link-grammar,ampli/link-grammar,opencog/link-grammar,linas/link-grammar,ampli/link-grammar,ampli/link-grammar,opencog/link-grammar,MadBomber/link-grammar,opencog/link-grammar,linas/link-grammar,opencog/link-grammar,linas/link-grammar,opencog/link-grammar,linas/link-grammar,linas/link-grammar,MadBomber/link-grammar,linas/link-grammar,MadBomber/link-grammar,MadBomber/link-grammar,ampli/link-grammar,linas/link-grammar,MadBomber/link-grammar,ampli/link-grammar,linas/link-grammar,opencog/link-grammar,ampli/link-grammar,opencog/link-grammar,MadBomber/link-grammar,MadBomber/link-grammar