another weird side effect of the line cache/logging stuff.
The true stderr is now stored in the "stderr" global variable and is
used to print the help screen.
"-H=windowsgui" disables stdout on Windows, and the io.Multiwriter used
for logging had stdout as it's first entry, which failed and caused
logging and line caching to be skipped. stdout is now removed from
the multiwriter in this situation. Other portion of the issue was
because crash reports had colons in their names, which Windows
doesn't like. Fixes#168.
Sometimes calls to app.err.Fatalf would fail to print the error to the
console, and fail to show "A crash report has been saves to...". Both of
these should be fixed now.
The last 100 lines of logs are now cached, and when a crash occurs, they
are saved to a file in the temp directory ("/tmp" on *nix), and pretty
HTML version is also created and opened in the browser.
* Currently only handles panics, will be included in more places soon
* Copy button and button to generate a GH issue will be added
