Changes to support different javac version

Dear Eric


The javac compiler settings are now configurable in ant.settings.
Not all <javac> tasks in build.xml had the same attributes set.

In particular, not specifying the encoding property reveals a usage of the currency sign (http://www.fileformat.info/info/unicode/char/a4/index.htm) in both jas.MethodHandleCP (line 27) and jas.InvokeDynamicCP (line 28).

It caused the following waring:
[javac] lib/jas/src/jas/InvokeDynamicCP.java:28: warning: unmappable character for encoding ASCII
[javac] uniq = (bsmClassName + "fv0?" + bsmName + "&%$91&" + bsmSig+ "*(012$" + methodName + "dfg8932" + methodSig).intern();
[javac]                                                ^
[javac] lib/jas/src/jas/MethodHandleCP.java:27: warning: unmappable character for encoding ASCII
[javac] uniq = kind + "$gfd?" + ownerName + "&%$91&" + fieldOrMethodName + "*(012$" + sig;
[javac]                               ^