Implement user settings functionality

[emcniece]

This commit adds the final user settings functions: Autoscroll, Line endings, Submit-on-enter, and visible scroll bars.

Other major changes:

• Timestamp generation moved down to terminal_print() for simplicity
• "Send Data" form click handlers changed to allow for enter key delegation
• Disabled a few console.log statements to move away from debug clutter as we approach MVP

[emcniece]

@kh90909 test, suggest and merge at will!

[kh90909]

I ran into a few issues with this...

• The visible scrollbars toggle in the modal resets to disabled upon reloading the page, but the scroll bars remain if they were turned on before reloading. If you change it to enable again, a second set of bars appears until the modal is dismissed. And it doesn't seem to be possible to get rid of the first set without clearing localStorage.
• When autoscroll is set to "when page at bottom", it seems to jitter noticeably when I try to scroll up from the bottom until I "escape". It seems like the "at bottom" detection is too greedy - a single click on the scroll bar up button doesn't break away from the scrolling.
• The line ending backslashes are getting escaped into double slashes in the event reported by the Particle Cloud (particle subscribe mine). Does JS support interpretation of escape sequences like these in strings, or do we need to manually replace with 0x0d / 0x0a?

Can we remove the horizontal scroll bar? The spec says everything in the terminal should wrap, so I don't think it's necessary. Also, I think the scroll bar on the sidebar should show only if the content doesn't fit on the screen. Is it possible to change the scroll bar colors or is it system controlled? The light grey bar messes with the dark color scheme!

Also, maybe it would be better to move the 'Visible Scroll Bars' row in the modal up above the Show/Hide section. Since the toggle is the same size as the one for "Submit on Enter", I think it will fit in better there.

[emcniece]

Did some research.

1. Visible Scrollbar setting - _.extend() is creating a duplicate setting during get_settings(), which is then double-processed when the button toggle labels are updated during restore_settings(). This behavior is due to the settings being an array instead of an object, so save_settings() will need to serializeArray into an object (easy transform). The surrounding settings handlers will need to be updated to work with an object as well.
2. Page bottom detection is done in terminal_print() by comparing window height, scroll position, and document height. The jitter problem happens when the user tries to scroll while the jQuery scrollTop animation is still executing, and the current scroll "greed" is set to 50px which seems to not be enough to use a single scrollbar click to escape. The jitter fix is to reduce the animation time (from 1000ms to 250ms), and the greed can be reduced safely to 30px.
3. No fix for line end escaping yet - need to test.

Other issues:

• Horizontal scroll issue fixed! Updated overflow to overflow-y.
• Sidebar scroll (when active in settings) now only shows when content overflows vertically
• Scrollbars have been styled, but this will only work on webkit browsers (not Firefox :-1: )
• "Visible Scroll Bars" setting row moved up

[emcniece]

Ready for demo: https://rawgit.com/emcniece/OakTerm/feat/i23-user-settings/index.html

Be sure to clear localStorage before testing!

[kh90909]

Hope you don't mind. I was working through the error handling and came across the line end escaping code and fixed it. I haven't had a chance to test the other updates yet. Once I do I'll merge it along with the escaping fix. Hopefully tomorrow.