String related improvements:

(1) Fix string.char and string.byte (argument indexing was off by one)
(2) Implement string.find
(3) Change calls to charAt, which does array bounds checking, in the
    pattern matcher with calls to luaByte, which does not.
(4) Replace use of recursion with while/continue in pattern matcher.

src/main/java/lua/value/LString.java

@@ -121,7 +121,32 @@ public class LString extends LValue {
 	public int charAt( int index ) {
 		if ( index < 0 || index >= m_length )
 			throw new IndexOutOfBoundsException();
-		return (int)m_bytes[ index ] & 0x0FF;
+		return luaByte( index );
+	}
+	
+	/** Java version of strpbrk, which is a terribly named C function. */
+	public int indexOfAny( LString accept ) {
+		final int ilimit = m_offset + m_length;
+		final int jlimit = accept.m_offset + accept.m_length;
+		for ( int i = m_offset; i < ilimit; ++i ) {
+			for ( int j = accept.m_offset; j < jlimit; ++j ) {
+				if ( m_bytes[i] == accept.m_bytes[j] ) {
+					return i - m_offset;
+				}
+			}
+		}
+		return -1;
+	}
+	
+	public int indexOf( LString s, int start ) {
+		final int slen = s.length();
+		final int limit = m_offset + m_length - slen;
+		for ( int i = m_offset + start; i <= limit; ++i ) {
+			if ( equals( m_bytes, i, s.m_bytes, s.m_offset, slen ) ) {
+				return i;
+			}
+		}
+		return -1;
 	}
 	
 	public static LString valueOf( double d ) {
@@ -356,6 +381,6 @@ public class LString extends LValue {
 	}
 
 	public int luaByte(int index) {
-		return m_bytes[m_offset + index];
+		return m_bytes[m_offset + index] & 0x0FF;
 	}
 }