Added access to MultiDimArray using operator[].

Includes tests.
Added cstring lib. to multidimarray header.

Some older compilers were complaining about the lack of a definition for memset.
New feature: Relative cond. level for te-extended.

This is activated by setting the flag `RelativeGlobalConditioningLevelQ` to true. It rescales the conditioning level to be between the minimum and maximum of the global signal.
Added relative cond. flag for all other measures.

For `te-extended`, this was done in the last commit.