Allow initialization from the project root

For example, from a Git bash prompt:
$ mkdir -p /c/repos/other && cd /c/repos/other
$ git clone -b windows git://github.com/wireddown/LabViewGitEnv.git
$ cd LabViewGitEnv
$ bin/LVBootstrap.sh --system

Since both LVInit.sh and LVBootstrap.sh need to
* process command line options,
* update git attributes, and
* configure git to use LVCompare and LVMerge,
refactor these operations into functions and place them in etc/LVUtilities.sh.
Detect the LabVIEW version to use for diff and merge

Change shell variable reference style to ${CurlyBraces}.
Minor text updates.
Simplify the diff and merge wrapper scripts

detect_labview_version is always callable, so there's no need to test for
it.
Merge pull request #3 from wireddown/windows

Detect the version and bitness of LabVIEW to use for LVCompare and LVMerge