test for "imshow"

Use the "imagesc()" function if "imshow()" doesn't exist.
use imagesc instead of imshow

use imagesc() instead of imshow()
Merge pull request #37 from gallamine/master

Have visualize check for "imshow()"s existance.
octave compatibility fixes
print training and validation errors
Currently, validation error is only used for plot in figure. In this commit, we try to print the validation error in terminal as well
Merge pull request #51 from ananda621/print_valerror

print training and validation errors
optional bias regularizer
Sometimes, bias weights are ignored from regularization as mentioned in UFLDL tutorials at http://ufldl.stanford.edu/wiki/index.php/Backpropagation_Algorithm. nn.biasPenaltyL2 is a boolean field that determines whether or not to use reguarlization on the bias weights. nnsetup() initializes this term to be true by default (which is the current configuration of the Toolbox) so this change will be backward compatible with any codes that uses this Toolbox
bugfix: L2 reguarlization is now not applied on bias terms
Merge pull request #52 from ananda621/optional_bias_regularizer

optional bias regularizer
modified runalltests to run on octave
deleted xunit
I added comments for some RBM parameters and a comment in tanh_opt.
I further applied some changes to rbmtrain, which I consider as elementary:
    - It is possible now to continue learning until the error doesn't change any further.
    - It is possible now to adjust the number of gibbs sampling steps.
I therefor introduced 2 new options:
    - opts.threshold to specify the threshold, how much the error has to change to abort learning. Default is 0.01.
    - opts.numsampleits to specify the number of gibbs sampling steps. Default is 1.
Note that no changes have to be done in order to keep the old behaviour.
I furthermore changed sigm and sigmrnd to use the builtin logistic_cdf function to benefit from potential optimisations of this function.
made some variable names self describing, corrected a typo
forgot to rename a variable
found typo
Merge pull request #61 from MaxG87/master

Some comments, enhancements to rbmtrain, minor changes.
Revert "found typo"

This reverts commit c66ef2b80b846096e82b423195d1f58f32addb0d.
Revert "forgot to rename a variable"

This reverts commit 4f51dbf175e3a04418d095e91968a4c8fb9c7038.
Revert "made some variable names self describing, corrected a typo"

This reverts commit c5c322f360577add2f1efa9b353bad2936a9b612.
Revert "I added comments for some RBM parameters and a comment in tanh_opt."

This reverts commit ce3c261ab06e76a80ff2c32e6b6382379cd0181a.