Amend description of SimpleCommand class
Fix spacing in file header comments

In some source files there was only one space before "*/" at the end of
the header comment while there were two in the other files. For
consistency, there should always be two spaces.

Note that we have (exceptionally) two spaces between each sentence in
header comments, while we have only one in normal comments.
Add checkheaderinclude.sh test script
Fix include guard macro name in SourceBuffer.hh

Include guard macro names should match the pathname.
Merge pull request #15 from magicant/fix/misc

Miscellaneous fixes