SQL Server typos and keyword completion modifier

[Sevin777]

This contains a few different things:

1. Fixed a few of typos in files related SQL Server mode
2. Added a few snippets and enhanced others for SQL Server mode
3. Override getCompletions for SQL Server mode to ensure proper case of completions and use intelligent meta instead of keyword for all completions.

3. Added completionModifier to text_highlight_rules, which is an optional function that can be specified by a mode's highlight rules that inherit from text_highlight_rules.
4. Modified getCompletions in text mode to call the completionModifier if it exists.

The completion modifier allows modifying keyword completions, which is useful for a few things:
- Remove keywords that are obsolete from the completor, but they still need to have syntax highlighting
- Modify the meta display in the completer to provide more information than keyword for some things
- Modify the case of completions, use case: SQL Server mode has completions that should be all caps, and others that should not (even though all keywords are case-insensitive for highlighting, its simply recommended by Microsoft to use all caps for most keywords).

I modified SQL Server mode to use the completion modifier, and I went ahead and modified Javascript mode as well.

If you don't like the completion modifier and the javascript modifications, I can remove them and simply do a one off for SQL Server mode completions by overriding getCompletions for SQL Server mode. I decided to make the completion modifier standard because I think it could benefit almost all modes.

Javascript mode completion popup with modified meta for keywords:

[nightwing]

I like the result of using completionModifier, however having it called from getCompletions doesn't seem to simplify the code, that is overriding getCompletions would require same amount of code which will work a bit faster. Also we could use information about obsolete keywords from the original keyword map instead of throwing it out at https://github.com/ajaxorg/ace/blob/master/lib/ace/mode/text_highlight_rules.js#L220

[Sevin777]

Good point. I think it would be valuable to have a standardized way to have create more intelligent keyword completions for each mode, but I don't have the time to figure out the best implementation.

I removed all changes that are not for SQL Server mode and added an override for getCompletions for SQL Server mode only. I am caching the result of this function as it takes ~15ms to execute (compared to ~1ms when there is no extra filtering). I don't see any harm in caching the result, do you?

UPDATE
I realized I can't cache the result of getCompletions because the filtering of the list references the cached result, which messes up subsequent calls. Caching would require a deep clone, which would be only marginally faster than not caching. I don't think there is an issue with waiting ~15ms to get the completions (Tern commonly waits ~1,000ms)

[nightwing]

Are you sure about caching? autocompleter doesn't modify array of matches it receives from getCompletions https://github.com/ajaxorg/ace/blob/master/lib/ace/autocomplete.js#L237.

[nightwing]

could we just use types skipping keywordList entirely?
keywordList removes some information that highlighter doesn't need and here we are restoring that using slow indexOf in a large array

[Sevin777]

Good point about skipping the keyword list, the custom completions is now simpler and its only compiled once.

[Sevin777]

I think this was the unnecessary rule you were referring to, correct? I think I copied that rule from somewhere else

[nightwing]

Merged.
Thanks!