Let LatexBox_LatexErrors handle status message

In addition, ensure that we do not need to "press enter to
continue" after successful compilations.  This is done simply
by adding a redraw just before the last echoed message.

Fixes main point of #112
Open quickfix with belowright, not botright

Fixes #112
Minor fix to informative output
Dont search for main tex file unless necessary

LatexBox has an autocommand that is triggered when buffers are
unloaded.  The autocommand calls LatexBox_LatexmkStop, in order
to clean up background processes.  This function looks for the
main tex file.  The update moves the search for the main tex file
name until after we know something should be done.

Fixes #111
Fixes basename not defined in LatexmkStop

The bug was introduced in 8b55dcf for a fix to #111.

Fixes #113
Bugfix: Error on compilation in dir with spaces.

Closes Issue #115.
Merge pull request #120 from AlexJF/fix_fname_with_space

Bugfix: Error on compilation in dir with spaces. Fixes #115
Parse secnum for non standard TOCs
Fixes #118

Note that this patch might be reverted if it is found to
break anything for anyone else.  It looks OK on my end.
Add option to set dynamic resize for TOC
Addresses #119

Let g:LatexBox_split_resize = 1 in your vimrc to set dynamic resize.
Added folding of TOC (#117)

The TOC can be folded by setting g:LatexBox_fold_toc = 1.
Fixed typo and minor bug (for #119)
Added option to hide TOC help text
Feature requested in #117

The option name is g:LatexBox_toc_hidehelp, and if this is
nonzero, the help text will be hidden.
Some modifications of TOC folding
Addresses #117

Added option g:LatexBox_fold_toc_levels to set number of levels to fold (max
3). Also added foldtext function.
Minor adjustment of dynamic columns
Use normal zv instead of normal zt (#117)
SecLine should take spaces into account (#117)
Fixed redirection for latexmk (#121)

1. For linux, also redirect stderr to /dev/null.
2. Do redirection also for vimserver (everything still works,
   but there might be reasons not to redirect to /dev/null
   that I am not aware off)

In addition, I made a minor fix for the pgrep command that finds the
PID (to ensure unique PIDs).
Added nospell option for TOC window (#122)
Option to specify environment variables to latexmk
Merge pull request #125 from stev47/env-option

Option to specify environment variables to latexmk