Process the -C option before running RUN_AFTER_FLAGS tools.

This brings the flag more inline with its description: "change to
DIR before doing anything else".

The use case is to make it possible to use -C together with -t msvc.
When debugging Windows builds, it's handy to be able to copy-paste
the commands from "ninja -v" and make them run in the correct
directory by adding this flag.
Added highlighting in Emacs for ${...} variables
Removed tab and added . in variable name regexp
Add highlighting of rule in build statements

Highlight the rule being used in a build statement.  Also add `.` to acceptable characters in a rule name and relax whitespace matching before the name.
Merge pull request #755 from zmodem/working_dir_vs_msvc_tool

Process the -C option before running RUN_AFTER_FLAGS tools.
Merge pull request #788 from donkopotamus/patch-2

Add highlighting of rule in build statements
Add NetBSD support.
It works fine under NetBSD/amd64 6.99.47.
Prepared load (-l N) support for windows.

Inspired by:
http://stackoverflow.com/questions/23143693/retrieving-cpu-load-percent-total-in-windows-with-c
Fixed/improved -l N documentation For windows

On windows "system load" is not so obvious term, added line explaining N
argument in -l N
Fixes for windows CalculateProcessorLoad

- Fixed bad logic condition,
- Added comment to clarify
Small usage info fix for windows
Improved load calculation

Added code to gracefully handle:
1. Call to CalculateProcessorLoad with not incremented ticks (fast calls
to GetSystemTimes can result same results),
2. Smooth/filter load estimation for consecutive calls.
Merge pull request #799 from ryo-on/netbsd-support

Add NetBSD support.
Fixed naming convention in GetLoadAverage support functions.
Changed implementation to provide load from 0 to ProcessorCount

This makes this implementation more consisten with POSIX load avarage.
Remove extra info from Usage()

As now behavior is similar on on platforms, this can probably be removed
Merge pull request #798 from kwesolowski/master

Provided Basic Support for -l N option on windows platform.
add some parens to silence a gcc warning
amend HACKING.md with instructions for Arch Linux
Merge pull request #802 from martine/parens

add some parens to silence a gcc warning