Bump version number of both lib and exe to 1.20.0
Require at least HTTP-4000.2.5

Prior versions didn't include an upper bound on network and might
therefore cause build failures as the relativeTo function was changed
in network-2.4.0.0.
Use 1.20.0.0 instead of 1.20.0 as the version number
Fix typo in HTTP upper bound
Update bootstrap.sh.

(cherry picked from commit a63871b7ed005fae265a9e8517e51c346e8c6b5a)

Conflicts:
	cabal-install/bootstrap.sh
More diff friendly pretty printing of cabal files

Added the new field constructor functions 'listFieldWithSep'
and 'commaListFieldWithSep' to be able to define pretty printing
for fields, where each value of the field is positioned on a new line.

Which fields are nested is currently hard coded in the 'ppField' function.

(cherry picked from commit e8d5ea254ab2ed037819bcd094146062ecca7a0b)
Add changelog for Cabal-1.20.0.0
Add changelog for cabal-install-1.20.0.0
Change network version bound to something sensible
Revert "Add cabal exec"

This reverts commit 99d912d321a750739475412c4510075675b2b91b.

Looks like Johan managed to botch a merge somehow, see #1786. Or maybe that was
a bug on the GitHub side.

(cherry picked from commit d10d67ccf2496fce5f6e38345f6338c816d0e4f3)
Merge branch '1.20' into exec

Conflicts:
	cabal-install/Main.hs