Update cygwin path replacements instructions

The server originally had a json file with the cygwin paths
commented out. However, this changed into a separate file
that needs to be renamed to the config.json file.
Allow using a custom path to the curl program.

This allows using omnisharp-emacs without changing your PATH environment
variable to contain the directory for the curl executable.
Bump version 1.8 -> 1.9
fontified eldoc - requires csharp-mode

semicolon so fontification won't error on some types

don't show semicolon
Async find usages and find implementations
doc strings
Make json deserialization errors more human-readable
Allow user to check whether the OmniSharpServer instance is alive

"Alive" means it is running and not stuck. It also means the connection
to the server is functional - I.e. The user has the correct host and
port specified.
Fix test helper macro giving wrong results

Omnisharp-host would not change
Fix alive status test always failing
Implement checking whether OmniSharpServer is ready
Re-implement flycheck for syntax errors

Closes #66

Revert "Remove syntax checking feature preview from README"

This reverts commit ff662301950bf13175114843e27efd4599774b4f.
Allow the flycheck error parser to work on code issues and QuickFixes

It used to only work on QuickFixes.
Add flycheck checker for code issues (refactoring suggestions)
Re-add "Start syntax check" to the menu
Make flycheck checkers use shared code for getting the curl command
Attempt to chain syntax errors -> code issues checkers

Doesn't work yet, but I can't figure out why not.
Finish chaining!
Allow fixing the first code issue on the current line

There is a new example mapping for this (for evil-mode): g f
this lets the OmniSharpServer fix the issue and inserts the new contents
returned by the server. The effect is instantaneous!
Don't force the user to use both flycheck checkers in order

The user may want to use either one or the other, or use them in a
different order (okay, maybe not). Flycheck provides ways of customizing
and ordering the provided checkers, and this should not be forced on the
user by omnisharp-emacs.