General doc updates.
General doc updates.

This provides a good number of general doc updates for the Mapping
base class. No functional changes of any sort.

YongYang86/dealii,danshapero/dealii,sairajat/dealii,YongYang86/dealii,gpitton/dealii,angelrca/dealii,JaeryunYim/dealii,nicolacavallini/dealii,JaeryunYim/dealii,YongYang86/dealii,gpitton/dealii,nicolacavallini/dealii,EGP-CIG-REU/dealii,ESeNonFossiIo/dealii,spco/dealii,gpitton/dealii,nicolacavallini/dealii,johntfoster/dealii,danshapero/dealii,andreamola/dealii,gpitton/dealii,shakirbsm/dealii,kalj/dealii,adamkosik/dealii,sriharisundar/dealii,johntfoster/dealii,johntfoster/dealii,jperryhouts/dealii,adamkosik/dealii,sriharisundar/dealii,sriharisundar/dealii,JaeryunYim/dealii,naliboff/dealii,angelrca/dealii,sairajat/dealii,spco/dealii,YongYang86/dealii,kalj/dealii,jperryhouts/dealii,danshapero/dealii,andreamola/dealii,EGP-CIG-REU/dealii,danshapero/dealii,ibkim11/dealii,shakirbsm/dealii,pesser/dealii,nicolacavallini/dealii,ibkim11/dealii,andreamola/dealii,EGP-CIG-REU/dealii,ibkim11/dealii,EGP-CIG-REU/dealii,maieneuro/dealii,jperryhouts/dealii,YongYang86/dealii,jperryhouts/dealii,spco/dealii,naliboff/dealii,spco/dealii,shakirbsm/dealii,sairajat/dealii,andreamola/dealii,naliboff/dealii,danshapero/dealii,ESeNonFossiIo/dealii,andreamola/dealii,kalj/dealii,angelrca/dealii,ESeNonFossiIo/dealii,pesser/dealii,JaeryunYim/dealii,gpitton/dealii,ibkim11/dealii,naliboff/dealii,danshapero/dealii,pesser/dealii,andreamola/dealii,pesser/dealii,Arezou-gh/dealii,gpitton/dealii,shakirbsm/dealii,johntfoster/dealii,sriharisundar/dealii,sairajat/dealii,ESeNonFossiIo/dealii,sairajat/dealii,Arezou-gh/dealii,spco/dealii,johntfoster/dealii,johntfoster/dealii,kalj/dealii,EGP-CIG-REU/dealii,danshapero/dealii,shakirbsm/dealii,naliboff/dealii,maieneuro/dealii,sriharisundar/dealii,ESeNonFossiIo/dealii,adamkosik/dealii,maieneuro/dealii,Arezou-gh/dealii,maieneuro/dealii,jperryhouts/dealii,nicolacavallini/dealii,angelrca/dealii,adamkosik/dealii,maieneuro/dealii,gpitton/dealii,ESeNonFossiIo/dealii,adamkosik/dealii,angelrca/dealii,jperryhouts/dealii,kalj/dealii,naliboff/dealii,adamkosik/dealii,Arezou-gh/dealii,maieneuro/dealii,EGP-CIG-REU/dealii,maieneuro/dealii,shakirbsm/dealii,adamkosik/dealii,kalj/dealii,pesser/dealii,pesser/dealii,ibkim11/dealii,Arezou-gh/dealii,JaeryunYim/dealii,pesser/dealii,sairajat/dealii,johntfoster/dealii,sairajat/dealii,ibkim11/dealii,ibkim11/dealii,Arezou-gh/dealii,ESeNonFossiIo/dealii,kalj/dealii,naliboff/dealii,shakirbsm/dealii,JaeryunYim/dealii,YongYang86/dealii,sriharisundar/dealii,Arezou-gh/dealii,spco/dealii,andreamola/dealii,nicolacavallini/dealii,spco/dealii,jperryhouts/dealii,angelrca/dealii,YongYang86/dealii,sriharisundar/dealii,JaeryunYim/dealii,angelrca/dealii,EGP-CIG-REU/dealii,nicolacavallini/dealii