BioAssaySetExporter uses incorrect alias names in queries

[Nicklas Nordborg]

When a formula column has been selected for export the BioAssaySetExporter uses the formula name as an alias in the query. It can't do that since the name may contain characters that are invalid in aliases.

Possible workaround: Change the name of all formulas to only use letters and numbers.

Here is the stacktrace:

net.sf.basedb.core.InvalidDataException: Alias 'A, log10(ch1 * ch2) / 2' has one or more invalid characters. Only a-z, A-Z and 0-9 is allowed.
at net.sf.basedb.core.query.Selects.expression(Selects.java:57)
at net.sf.basedb.plugins.BioAssaySetExporter.exportBaseFileSerial(BioAssaySetExporter.java:298)
at net.sf.basedb.plugins.BioAssaySetExporter.run(BioAssaySetExporter.java:937)
at net.sf.basedb.core.PluginExecutionRequest.invoke(PluginExecutionRequest.java:88)
at net.sf.basedb.core.InternalJobQueue$JobRunner.run(InternalJobQueue.java:420)
at java.lang.Thread.run(Thread.java:595)

[Nicklas Nordborg]

(In [3451]) Fixes #588