Separate sentences in guide-shell-loop

Thanks to @wltrimbl for the catch.
Grammar fix in swc-git

Thanks to @ahmadia.
Typo correction

Correct some typos point by @ahmadia.

Note: This commit have been amending.
Merge pull request #46 from r-gaia-cs/css

Solve issue #44
Spelling and capitalization consistency
Added new section on floating point arithmetic
Edited the list of objectives
DOC update `order` variable in `lesson\swc-shell\tutorial.html`
DOC update lessons' link of index.html
Adding a figure to the database filters lesson
Merge pull request #70 from HaveF/swc_shell_lost_temple

DOC add lost part(intro) to the swc-shell
Merge pull request #78 from HaveF/first_page_link_update

DOC update lessons' link of index.html
Add explanation for "no output behavior" of cd
Add additional heading, move 'no output box' down a bit
removed aggravating comma
Merge pull request #80 from ChristinaLK/making-changes

Adding a figure to the database filters lesson
removed whitespace per @ethanwhite
Merge pull request #65 from cmacdonell/improvements

Add field names to tables and image to illustrate join
Add notes from summer 2013 bootcamps
Merge pull request #52 from r-gaia-cs/git-editor

Add editor for GNU/Linux in swc-git