added library DatatypeSimps in src/datatype

The datatype package stores information about created datatypes in TypeBase.
This library accesses this information and provides useful theorems and simpsets.
These are especially designed to handle the explicit usage of case-constants. There is
support for

- simple rewrites for datatypes
- expanding universal and existential quantifiers
- lifting and unlifting case-constants (similar to COND_LIFT_ss for bool)
- congruence theorems for usage with the simplifier (warning: slow)
- moving case-splits to the top-level of equational theorems. This is useful for
  e.g. transforming definitions into a form more handy for rewriting.
Italian translations of Logic and Description sources
Merge branch 'master' of https://github.com/domasin/HOL
Merge pull request #139 from domasin/master

Italian translations of Tutorial and Logic sources
Adapt behaviour of l3_arm_triples (in arm_decompLib),

Provides better handling of load (pc relative) instructions.
Update to ARM model.

Fixes MSR (banked register) and MRS (banked register) instructions, in accordance with corrections made within the ARM ARM.
Syntax support for PAD_LEFT and PAD_RIGHT.
Support for PAD_LEFT and PAD_RIGHT.
enumfset cleanups, including removal of parsing inside fn bodies.

From Lockwood Morris.
Tweak/experiment-with the way Travis sends build notifications.
Create a selftest for enumfset directory.

Code comes from Lockwood Morris.
Make Poly/ML Holmake output something when emulating HOLMOSMLC etc.

When a makefile rule wasn't a special one featuring $(HOLMOSMLC), the
command was output (just as in regular make), but when the emulation
kicked in, the "compilation" happened silently.

The messages are not a copy of the mosml command-line (which is not
being run), but rather a reflection of the arguments being passed to
the underlying code.
Fix dependencies for selftest.exe in enumfset's Holmakefile.
Try to get Travis's IRC notifications working (correct syntax helps)
s/chat/irc/ in Travis notification config
Clean up some code in patriciaLib.

The code for PTREE_PEEK_CONV is now a bit less opaque and ever so slightly faster. Quite a few of the other conversions could do with similar treatment.
Further small improvements to PTREE_PEEK_CONV.

Squeezes out a tiny bit more performance. The wordsLib conversion BIT_SET_CONV has been updated and is now exported.
Add BIT_SET syntax functions to wordsSyntax signature.
Provide more options for futzing with ='s precedence

Now there are four functions:

  {temp,}_{tight,loose}_equality

The temp versions create an effect that is not exported in the theory
file, and can be called before new_theory without causing annoying
error messages about changes being discarded.

The tight precedence is 450, which is the same level as the other
standard relational operators (e.g., <). The loose precedence is 100,
which is historical, and clearly appropriate for = construed as iff.
Fiddle with datatype printing in TeX (with selftest of sorts)