Start working to make this book complete!
By finishing The Basic Concepts.
To the glory I dreamed of.
# of unary operators: 5 -> 6.
Merge pull request #54 from hiroshi-manabe/unary-number-fix

# of unary operators: 5 -> 6.
non-throwing -> NOT non-throwing.
Merge pull request #55 from hiroshi-manabe/fix-noexcept

non-throwing -> NOT non-throwing.
Finished linkage.
Merge branch 'gh-pages' of https://github.com/EzoeRyou/cpp-book into gh-pages
Fixed typos.
Merge pull request #56 from hiroshi-manabe/fix-typo-linkage

Fixed typos.
Finished storage duration.
Merge branch 'gh-pages' of https://github.com/EzoeRyou/cpp-book into gh-pages
Fix typo XML element
Merge pull request #57 from makotokato/typo-xml

Fix typo XML element