Fix compilation problem for sqlite versions between 3.5.0-3.7.7. ROOT-5318.

Patch provided by Oliver Freyermuth.
The version 1.2.23 of libpng was the built-in version in ROOT. It had some security issuee. Now we have 1.2.50.
cf: https://sft.its.cern.ch/jira/browse/ROOT-5322
More correct storage format for timestamps. Fix ROOT-5330.

Solution attached as patch:
- SetTimestamp() writes timestamps of the format "2013-06-30 05:11:01.021"
  to the database and communicates the 3-digit precision (i.e., milliseconds)
  to the user in its comment. 3 digit precision is also what the strftime /
  datetime methods of sqlite use, all other digits are ignored by those methods.
- GetTimestamp() reads such timestamps, also limiting the fraction-precision
  to 3 digits and communicating that to the user from within the comment.

Patch by Oliver Freyermuth.
More correct storage format for timestamps. Fix ROOT-5331.

Solution attached as patch:
- SetTimestamp() writes timestamps of the format "2013-06-30 05:11:01.021"
  to the database and communicates the 3-digit precision (i.e., milliseconds)
  to the user in its comment. 3 digit precision is also what the strftime /
  datetime methods of sqlite use, all other digits are ignored by those methods.
- GetTimestamp() reads such timestamps, also limiting the fraction-precision
  to 3 digits and communicating that to the user from within the comment.

Patch by Oliver Freyermuth.
zlib should be included from a different place on windows.
fix coverity issue.
Fix hanging context menu for TQtWidget canvas. Fixes ROOT-4031.
ignore tutorials/tree/basic.root.
Added paranthesys around expressions multiplied by units so that the unit applies to a combined tag and not only to the last term
import the mods (from the trunk) allowing to change the line attributes for legos. As suggested here :
http://root.cern.ch/phpBB3/viewtopic.php?f=3&t=16560
Adding enum to TBranchElement to clarify Type numbers

(cherry picked from commit caec9c2a21b520cd456041b77fcda0b52d8ab286)

Conflicts:
	tree/treeplayer/src/TTreeReaderValue.cxx
Added method to get the size of the class

(cherry picked from commit beafe941588df210e50d209fc951bcace6181a1f)
Fix TClass::GetClassSize() to also work for CollectionProxy case: use Size().

(cherry picked from commit 6fecd500190c9f08edd6f2e03c5cf5ec8770d707)
Remove stray "," in enum constant list.
Added enums for sub-branches of STL and Clones, and moved Class getter to being public

(cherry picked from commit bafd944e918a05824d6afc7344fdc70cfc153103)

Conflicts:
	tree/tree/inc/TBranchElement.h
	tree/treeplayer/src/TTreeReaderArray.cxx
	tree/treeplayer/test/hardTreeReaderTest.cpp
Coding convention; rename some enum constants.