Update underlying implementation using prior (penalized likelihood)

[hkim89]

• Add getKc function to pre-estimate Kc.
• Add gene1Scan and additional gene2Scan incorporated with getKc to pre-estimate Kc inside those functions, so that users can either separately pre-compute Kc with getKc and eigen decompose it as input arguemnts for geneScan and existing gene2Scan functions or do not need to do such steps.
• Update geneScan, gene2Scan, permTest functions by adding prior distribution of Inverse-Wishart for numerical stability and efficient computation and update documents.
• Correct and update test files and passing 100 %