Fix Kernel.#set_trace_func

Fix example and klass parameter of proc.
fix typo
fix typo
Merge pull request #89 from guemon/master

fix typo
add @see to String#split
Update IO.popen
Merge branch 'master' of github.com:rurema/doctree
Update about gem search. (closes gh-76)
Update IO.popen
Update Kernel.#spawn about file descriptors, :close_others and :close options
update links. (refs gh-90)
Merge pull request #85 from yui-knk/fix-set_trace_func

Fix Kernel.#set_trace_func
Fix typo.
Merge pull request #92 from yui-knk/fix-typo-drb

Fix typo.
Update the description of string literals specified by \unnnn and \u{nnnn} (see #79).
Update the description of literal regexp specifed by \u{HHHHHH ...} (closes #79)
Merge branch 'master' of github.com:rurema/doctree
Remove unsupported regexp literal (closes #80).
add Numeric#nonzero? example. (refs gh-94)
add links Numeric#zero? and #nonzero?.