Unify build paths in all MSBuild VS projects and extract common build
logic into functions.

Note that this change changes both VS2010 and VS2013 projects to have
more predictable output paths and fixed output file name (pugixml).

Also improve linkage description

We'd like to build pugixml with both static & dynamic CRT and put it
all in one NuGet package.

CoApp sort of allows us to do this via dynamic/static pivots, but it
does not let us customize the names of the pivots and additionally has
some bugs with the project setup. Their project modifications are also
much more complicated - really, at this point we should do this
ourselves.

Create a simple native NuGet package with Linkage setting that picks the
right library, and package all libraries appropriately. Note that we use
the unified path syntax to make it simple to just get the right .lib
file from the toolset/platform/configuration/linkage combo.

Correctly check for error codes and don't run .bat file since it doesn't
work anyway (the variables it sets aren't accessible in PowerShell, and
the path to the script doesn't seem to be the same in VS2017).

We used to use the current timestamp when building the archive; switch to using
the timestamp of the tag with the version we're packaging.

This requires some monkey patching since tarfile module is always using current
timestamp when writing gzip header...

Also exclude archive.py from archive and simplify release file list in Makefile.

Put debugging information into the object file so that it can be shipped
with NuGet binaries. Based on the linker settings for the executable
debug info will either be put into the final .PDB or stripped out.

Fixes #110.

Merge USEOWNSUBDIR and PKGCONFIG build flags; move the pkg-config source file
to scripts/.

This pivot seemed to be causing issues because the NuGet package thought it was actually dynamic.

Include more configurations in the Nuget package.

Having CMakeLists.txt in the project root makes it so much easier to use pugixml
as an external dependency in another CMake project.

Also remove top-level LICENSE file since .podspec already has it.

embed license to podspec, as LICENSE file is not in 1.7 tag, cocoapods errors otherwise. Get sources from zeux github

Git warns when it finds "whitespace errors". This commit gets
rid of these whitespace errors for code and adoc files.

Also refactor to use the same case and run after common options.

This avoids linker warning when building the final executable and we don't
have to package the .PDB file.

Move pugixml project file for VS2015 to scripts/ and unify the output file
structure similar to old VS201x projects. Remove test projects and solution
since they are not required for building.

Provide more accurate information in the package script and handle build
errors during package construction properly.