Make Profiler compile on Windows7.1SDK

Committed changes (afaik) will not affect original build environment.

To compile OpenCover.Profiler on Windows7.1SDK platform toolset using
VS2010 and/or SharpDevelop:

1) Instal Windows 7.1 SDK

2) In OpenCover.Profiler.vcxproj change all
-    <PlatformToolset>v110</PlatformToolset>
+    <PlatformToolset>Windows7.1SDK</PlatformToolset>

3) In OpenCover.Profiler project properties
define _TOOLSETV71 preprocessor symbol for
C++ Preprocessor AND
MIDL Preprocessor
New method returning end of BR-Instructions chain

Given Instruction toFollow argument, method will follow and skip all
unconditional branches and return last not BR instruction in the
unconditional-branches-chain.
Change Instrumentation Order

Instrument Branch-Points before Sequence-Points Instrumentation, because
Sequence-Points Instrumentation breaks unconditional CEE_BR chains.
Prepare SeqPoint Instrumentation for quick change

Prepare Method::InsertInstructionsAtOriginalOffset for inserting
Sequence-Point Instrumentation instructions at EndOfBranch
Backup
"Unvisited" default: switch branch coverage

Goal: To join unvisited switch default: branch with earlier by compiler
inserted conditional branch.
Why? To cover in fact visited branch that is due compiler rewriting
reported as unvisited.
How: Branch instrumentation for all switch(default) and for all
conditional br instructions (if branch, not else branch!), where exists
unconditional-branch-jump-chain, is "pushed down". Last conditional jump
(if exists) is rewired to inserted instrumentation.
Branch-Point attributes extended (coverage.xml)

Branch-Point path is tracked from existing Offset via (new) Offset-Chain
to (new) Offset-End attribute. In example:
<BranchPoint vc="0" uspid="13378" ordinal="8" offset="108" path="0"
offsetchain="121 143" offsetend="148" />
default: switch branch coverage improved
default: switch branch, much better

Almost done :) Conditional compilation removed
default: switch branch, good
default: switch branch - join only SequencePoint

Join/merge is limited to branches originated from single SequencePoint
Refactoring
Fix xml comment warning
minor tidy
Merge branch 'master' of https://github.com/ddur/opencover into ddur-master
remove asserts that assumed jumps were only forward
re-enable COR_PRF_DISABLE_ALL_NGEN_IMAGES to ignore all NGENd images (even NGEN /Profile images) #188
update version