Created Filter For Template Variables

Created new 'mlw_qmn_text_variable' filter to extend variables. Created new $mlw_qmn_result_array to pass results data to the filter.
Created Template Variable File
Added All Variables To New Variable File

Since I created the variable filter, it would be best to move all the main variables into the system as well. This file contains all the current variables for the quiz.
Added Include For New Variable File
Removed Old Variable Code

Since the variables are now in a new separate file and hooks into the filters, I removed the code from here.
Added Filter For Variables On Quiz Page

Added new filter mlw_qmn_template_variable_quiz_page for variables on quiz page and renamed results page variable to filter to mlw_qmn_template_variable_results_page.
Fixed Missing Comma
Updated Filter Name, New Variable, New Filter Hook

Added the functions for the new mlw_qmn_template_variable_quiz_page filter. Updated the name of the other filters. Added variable for display name.
Fixed Misspelling Of Filter
Fixed Misspelling Of Filter
Added Certificate Link To Results Array For Filter
Added Certificate Link Variable
Added Certificate Link Empty Into Array
Merge pull request #51 from fpcorso/feature/variable_filter

Added Filters For Variables Resolves #41