Splits the progress @echo statements in the Makefile.
Replaces some @echo recipes by @printf.

The echo command does not understand the -n argument on Mac OS X.
This is due to the fact that:

  - Makefile calls /bin/sh to execute a command
  - in Mac OS X, /bin/sh is a link to bash
  - in Mac OS X, bash is compiled with --enable-strict-posix-default

Therefore, the echo command does not have the -n argument.

printf on the other hand is a builtin function that works well on Mac OS X and Linux.
Moves one @printf statement to be more accurate.
Modifies the Makefile to use local npm install **when available**

The change introduced in 5bd8cdca9 was:

  - partial, as not all the command were translated
  - preventing the use of a global npm installation
Allows the user to set different source and destination in Makefile.

A user can use the following command to determine where to copy the resulting css file:

    $ BOOTSTRAP=<my-path> make
Changes some more commands to use the local npm install.
Fixes #6794: incorrect docs mention of th element
Merge branch '2.3.0-wip' into 3.0.0-wip

Conflicts:
	docs/assets/css/bootstrap.css
	less/type.less
Remove base-css.html after recent merges
Forgot to remove base-css.mustache
Add justified button groups for link buttons; reorganize dropdowns and button groups docs sections
Increase margins and line-height on h3; overhaul button dropdown docs
simpler breadcrumbs docs
pagination docs cleanup
reorder counters docs
mo betta thumbnails docs
simpler alerts docs
reorganize progress bars docs
simplify media docs
Merge branch '2.3.0-wip' into 3.0.0-wip

Conflicts:
	docs/assets/css/bootstrap-responsive.css
	docs/assets/css/bootstrap.css
	docs/examples/hero.html
	less/buttons.less
	less/carousel.less
	less/close.less
	less/dropdowns.less
	less/labels-badges.less
	less/mixins.less
	less/navbar.less
	less/navs.less
	less/pagination.less
	less/responsive-navbar.less
	less/scaffolding.less
	less/sprites.less
	less/thumbnails.less
	less/type.less