Blurb:: File containing advanced QUESO/GPMSA options

Description:: 
Allow power users to override default QUESO/GPMSA options
such as hyper-parameter priors, initial chain position, and proposal
covariance (including hyper-parameters), which might not be accessible
through Dakota user input.

<b> Default Behavior </b>
No advanced options used.

<b> Usage Tips </b>
The \c options_file offers a final override over other options
settings, which are applied with the folowing precedence:
<ol>
<li>QUESO library defaults</li>
<li>Dakota hard-coded defaults</li>
<li>Settings from Dakota input file</li>
<li>Settings from the advaned \c options_file</li>
</ol>

Examples::

\verbatim
# FILE: dakota_gpmsa.opts

# Base QUESO Environment options
env_subDisplayFileName   = QuesoDiagnostics/display
env_subDisplayAllowedSet = 0 1
env_displayVerbosity     = 2
env_seed                 = 2460

# GPMSA Options
gpmsa_emulator_precision_shape = 2.0
gpmsa_emulator_precision_scale = 0.2
gpmsa_emulator_correlation_strength_alpha = 1.0
gpmsa_emulator_correlation_strength_beta = 0.1
gpmsa_discrepancy_precision_shape = 1.0
gpmsa_discrepancy_precision_scale = 1e4
gpmsa_discrepancy_correlation_strength_alpha = 1.0
gpmsa_discrepancy_correlation_strength_beta = 0.1
gpmsa_emulator_data_precision_shape = 3.0
gpmsa_emulator_data_precision_scale = 333.333
\endverbatim
