Factorize prior bound and definiteness checks

also removes useless isestimation check

matlab/utilities/general/isestimation.m

-function b = isestimation(option)
-
-% Returns true if we are currently estimating a model.
-
-% Copyright (C) 2017 Dynare Team
-%
-% This file is part of Dynare.
-%
-% Dynare is free software: you can redistribute it and/or modify
-% it under the terms of the GNU General Public License as published by
-% the Free Software Foundation, either version 3 of the License, or
-% (at your option) any later version.
-%
-% Dynare is distributed in the hope that it will be useful,
-% but WITHOUT ANY WARRANTY; without even the implied warranty of
-% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-% GNU General Public License for more details.
-%
-% You should have received a copy of the GNU General Public License
-% along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
-
-b = false;
-
-if ischar(option.mode_compute) || option.mode_compute || option.mh_replic
-    b = true;
-end
\ No newline at end of file